Thermosensitive recording material and color developer compound therefor

ABSTRACT

A thermosensitive recording material has a support and a thermosensitive coloring layer formed thereon containing a leuco dye and a color developer capable of inducing color formation in the leuco dye upon application of heat thereto, with the color developer including at least one compound (A) having in a molecule thereof at least two aromatic ring moieties with specific structures, selected from the group consisting of an aromatic ring moiety having at least one carboxyl group and electron-attracting functional group, an aromatic ring moiety having at least one carboxyl group and electron-donating functional group, and an aromatic ring moiety having at least one carboxyl group, free of the electron-attracting and electron-donating functional groups. An aromatic carboxylic acid compound serving as the above-mentioned compound (A) and the producing method thereof are also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermosensitive recording materialcomprising as the main components a leuco dye serving as a coloringagent and a color developer capable of inducing color formation in theleuco dye upon application of heat thereto. In addition, the presentinvention also relates to an aromatic carboxylic acid compound useful asthe color developer for use in the thermosensitive recording material,and the production method of the above-mentioned compound.

2. Discussion of Background

Generally, a thermosensitive recording material comprises a support anda thermosensitive coloring layer formed thereon, which comprises as themain components a colorless or light colored electron-donating dyeprecursor, and an electron-accepting color developer. These dyeprecursor and color developer are caused to react instantaneously uponthe application of heat thereto to produce recorded images, forinstance, using a thermal head, heat pen or laser beam, as disclosed inJapanese Patent Publications 43-4160 and 45-14039.

A thermosensitive recording material is used in a wide variety offields, for example, as the recording material for an electroniccomputer, facsimile apparatus, ticket vending apparatus, label printer,and recorder because it has the advantages that recording can beachieved using a relatively simple apparatus, maintenance is simple, andthere is no noise development.

The above-mentioned thermosensitive recording material employing such anelectron-donating dye precursor and an electron-accepting colordeveloper has excellent characteristics such as good appearance and nicetouch and is capable of producing images with high coloring density, butalso has the disadvantage that the image preservability thereof is poor.To be more specific, when image areas formed in the thermosensitiverecording material come in contact with plastics such as polyvinylchloride, images are decolorized by plasticizers and additives containedin such plastics, or when the image areas come in contact with chemicalscontained in foods or cosmetics, such image areas are easily decolorizedor the background is easily colored.

To improve the preservation stability of the image recorded in thethermosensitive recording material, it is proposed to use colordevelopers with high reliability. For instance, the use of aphenolsulfone compound as the color developer is disclosed in JapaneseLaid-Open Patent Applications 58-82788 and 60-13852; a metallic salt ofbenzoic acid, disclosed in Japanese Laid-Open Patent Application61-47292; and a substituted salicylic acid compound, disclosed inJapanese Laid-Open Patent Application 62-169681. However, even thoughthe aforementioned compounds are used as the color developers, thefastness to plasticizers of the image areas formed in thethermosensitive recording material is not sufficient.

Furthermore, the use of a monoester of nitrophthalic acid is proposed inJapanese Laid-Open Patent Application 62-80089, but this compound isunsatisfactory in terms of the fastness to plasticizers of the imageareas formed in the thermosensitive recording material. In addition, asulfonylurea-group-containing compound is used as the color developer inJapanese Laid-Open Patent Application 6-255262. When this type ofcompound is used as the color developer, the coloring sensitivityextremely deteriorates although the fastness to plasticizers of theimage area is improved.

In Japanese Laid-Open Patent Application 9-267566, it is proposed to useas the color developer a compound excluded in the present invention,that is, a compound (B) as will be described in detail later, andmetallic salts thereof. However, these compounds have the shortcomingsthat the image area formed in the thermosensitive recording material isreadily decolorized under the circumstances of high temperature.

By the way, it is believed that synthesis of a nitrophthalamide dimer,in particular, a 3-nitrophthalamide dimer can be achieved by amidationreaction of 3-nitrophthalic acid by use of an amine compound. A reactionbetween 3-nitrophthalic anhydride and an amine compound is reported, forexample, in IDDIAN J. CHEM., VOL. 7, 634-635 (1969) and J. Am. Chem.Soc., Vol. 57, 1064-1065 (1935). According to those references, as shownin the following reaction schemes (1) and (2), the amidation reaction of3-nitrophthalic anhydride takes place at the 1-position of3-nitrophthalic acid due to steric hindrance when an aromatic primaryamine such as aniline is used as the amine compound; while the amidationreaction is carried out at the 2-position thereof when ammonium is usedas the amine compound because this reaction is less subjected to sterichindrance.

[Reaction Schemes]

It is considered that the difference in reactivity as shown in thereaction schemes (1) and (2) results from the steric hindrance causedwhen carbonyl group in 3-nitrophthalic anhydride is attacked by an aminecompound.

When 3-nitrophthalamide dimers of the following formulas (V) and (VI)were separately synthesized by allowing 3-nitrophthalic anhydride toreact with a diamine compound under the same conditions as stated in theaforementioned references, there was obtained a mixture of the isomersof formulas (V) and (VI).

wherein Y represents, for example, an alkylene group having 2 to 12carbon atoms, a xylylene group,

In this case, although those two 3-nitrophthalamide dimers (V) and (VI)can be isolated from each other, each compound cannot be efficientlyobtained as a pure product because the separation is very difficult.

Further, the aforementioned 3-nitrophthalamide dimers (V) and (VI) canbe independently synthesized in accordance with the following reactionschemes (3) and (4):

[Reaction Schemes]

However, the above-mentioned reaction schemes (3) and (4) are very longand include complicated reaction steps, so that they are not practical.There is increasing a demand for the establishment of efficientsynthesis method.

SUMMARY OF THE INVENTION

Accordingly, a first object of the present invention is to provide athermosensitive recording material capable of producing recorded imagestherein which images are superior in preservation stability, inparticular, the oil resistance, the plasticizer resistance, and the heatresistance.

A second object of the present invention is to provide an aromaticcarboxylic acid compound which is useful as the color developer, whenused in the thermosensitive recording material, capable of producingrecorded images with improved preservation stability.

A third object of the present invention is to provide a method ofproducing the above-mentioned aromatic carboxylic acid compound, inparticular, a 3-nitrophthalamide dimer, in the form of a pure productwithout including the isomers thereof.

The above-mentioned first object of the present invention can beachieved by a thermosensitive recording material comprising a supportand a thermosensitive coloring layer formed thereon comprising a leucodye and a color developer capable of inducing color formation in theleuco dye upon application of heat thereto, with the color developercomprising at least one compound (A) having in a molecule thereof atleast two aromatic ring moieties selected from the group consisting of(i) an aromatic ring moiety having at least one carboxyl group and atleast one electron-attracting functional group, (ii) an aromatic ringmoiety having at least one carboxyl group and at least oneelectron-donating functional group, and (iii) an aromatic ring moietyhaving at least one carboxyl group, free of the electron-attractingfunctional group and the electron-donating functional group, providedthat from compounds having two of the aromatic ring moieties (iii)serving as the compound (A), a compound of the following formula (B) isexcluded:

wherein G is —C_(n)H_(2n−2)— (in which n is an integer of 2 to 6),

(in which n is an integer of 2 to 6),

In the thermosensitive recording material of the present invention, itis preferable that at least two of the aromatic ring moieties for use inthe compound (A) be bonded by ester linkage or amide linkage, and thatthe aromatic ring moieties in the molecule be different.

Further, it is preferable that the above-mentioned electron-attractingfunctional group be selected from the group consisting of nitro groupand ester group, and that the electron-donating functional group beselected from the group consisting of hydroxyl group, alkoxyl group andsulfonyloxy group.

In addition, the thermosensitive recording material may further comprisean intermediate layer, which is provided between the support and thethermosensitive coloring layer and comprises minute spherical voidparticles comprising a thermoplastic resin.

The second object of the present invention can be achieved by anaromatic carboxylic acid compound of formula (I):

wherein R¹ and R² optionally are the same or different and are each ahydrogen atom, nitro group, hydroxyl group, an alkoxyl group,sulfonyloxy group, an alkyl group, an aralkyl group, an aryl group, analkyloxycarbonyl group, an aralkyloxycarbonyl group or anaryloxycarbonyl group; and X is —NHYHN— group or —OZO— group,

in which Y is an alkylene group having 2 to 12 carbon atoms, a xylylenegroup,

Z is an alkylene group having 2 to 12 carbon atoms, a xylylene group, anoxalkylene group, a bisoxalkylene group, a trioxalkylene group,

provided that when R¹ and R² are each hydrogen atom, X is not —NHYHN—group in which Y represents an alkylene group having 2 to 12 carbonatoms, a xylylene group,

The third object of the present invention can be achieved by a method ofproducing an aromatic carboxylic acid compound of formula (I′):

wherein Y is an alkylene group having 2 to 12 carbon atoms, a xylylenegroup,

comprising the step of allowing a nitrophthalic anhydride of formula(II) to react with a compound of formula (III):

wherein X is —NHYHN— group in which Y is the same as that previouslydefined.

Further, the third object of the present invention can be achieved by amethod of producing an aromatic carboxylic acid compound of formula (V):

wherein Y is the same as that previously defined in formula (I′),

comprising the step of allowing 3-nitrophthalic anhydride to react witha diamine compound of formula (IV) using a reaction solvent selectedfrom the group consisting of acetic acid, tetrahydrofuran andnitrobenzene:

H₂N—Y—NH₂  (IV)

 wherein Y is the same as that previously defined.

Furthermore, the third object of the present invention can also beachieved by a method of producing an aromatic carboxylic acid compoundof formula (VI):

wherein Y is the same as that previously defined in formula (I′),

comprising the steps of dissolving 3-nitrophthalic anhydride in aceticanhydride to prepare an acetic anhydride solution of 3-nitrophthalicanhydride, and adding a diamine compound of formula (IV) in smallportions to the acetic anhydride solution of 3-nitrophthalic anhydrideso as to dissolve the diamine compound in the acetic anhydride solution:

H₂N—Y—NH₂  (IV)

 wherein Y is the same as that previously defined.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is an IR spectrum of a compound No. 1 obtained in PreparationExample 1.

FIG. 2 is an IR spectrum of a compound No. 3 obtained in PreparationExample 2.

FIG. 3 is an IR spectrum of a compound No. 4 obtained in PreparationExample 3.

FIG. 4 is an IR spectrum of a compound No. 5 obtained in PreparationExample 4.

FIG. 5 is an IR spectrum of a compound No. 6 obtained in PreparationExample 5.

FIG. 6 is an IR spectrum of a compound No. 10 obtained in PreparationExample 6.

FIG. 7 is an IR spectrum of a compound No. 11 obtained in PreparationExample 7.

FIG. 8 is an IR spectrum of a compound No. 12 obtained in PreparationExample 8.

FIG. 9 is an IR spectrum of a compound No. 15 obtained in PreparationExample 9.

FIG. 10 is an IR spectrum of a compound No. 22 obtained in PreparationExample 10.

FIG. 11 is an IR spectrum of a compound No. 26 obtained in PreparationExample 11.

FIG. 12 is an IR spectrum of a compound No. 27 obtained in PreparationExample 12.

FIG. 13 is an IR spectrum of a compound No. 28 obtained in PreparationExample 13.

FIG. 14 is an IR spectrum of a compound No. 23 obtained in PreparationExample 14.

FIG. 15 is an IR spectrum of a compound No. 50 obtained in PreparationExample 17.

FIG. 16 is an IR spectrum of a compound No. 54 obtained in PreparationExample 18.

FIG. 17 is an IR spectrum of a compound No. 55 obtained in PreparationExample 19.

FIG. 18 is an IR spectrum of a compound No. 56 obtained in PreparationExample 20.

FIG. 19 is an IR spectrum of a compound No. 51 obtained in PreparationExample 21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The thermosensitive recording material of the present inventioncomprises as the color developer at least one compound (A) having in amolecule thereof at least two aromatic ring moieties selected from thegroup consisting of:

(i) an aromatic ring moiety having at least one carboxyl group and atleast one electron-attracting functional group,

(ii) an aromatic ring moiety having at least one carboxyl group and atleast one electron-donating functional group, and

(iii) an aromatic ring moiety,having at least one carboxyl group, freeof the electron-attracting functional group and the electron-donatingfunctional group,

provided that from compounds having two of the aromatic ring moieties(iii) serving as the compound (A), a compound of formula (B) isexcluded:

 wherein G is —C_(n)H_(2n−2)— (in which n is an integer of 2 to 6),

 (in which n is an integer of 2 to 6),

Examples of the above-mentioned compound (A) include a compoundrepresented by the following formula (VII):

wherein R¹ and R² optionally are the same or different and are each ahydrogen atom, nitro group, a halogen atom, cyano group, carbonyl group,sulfonyl group, hydroxyl group, an alkoxyl group, sulfonyloxy group, analkyl group, an aralkyl group, an aryl group, an alkyloxycarbonyl group,an aralkyloxycarbonyl group, or an aryloxycarbonyl group; and X is—NHYHN— group or —OYO— group,

in which Y is a bivalent group derived from an aliphatic hydrocarbon, abivalent group derived from an aliphatic hydrocarbon which has at leastone hetero atom, carbonyl group, sulfonyl group, ester linkage andaromatic ring in the main chain thereof, or a bivalent group derivedfrom bivalent aromatic hydrocarbons which are bonded by at least onehetero atom, carbonyl group, sulfonyl group, ester linkage, alkylene, oran aliphatic hydrocarbon including a hetero atom in the main chainthereof.

Specific examples of Y include an alkylene having 1 to 8 carbon atoms,an oxalkylene, a bisoxalkylene, a trisoxalkylene, xylylene, phenylene,biphenylene, naphthylene, and a bivalent group represented by thefollowing formula:

wherein A represents an alkylene group which may have ester group,sulfonyl group, or ether linkage.

To be more specific, Y represents the following groups;

In the formula (VII), R¹ and R² may be different in the moleculethereof, as mentioned above.

In the present invention, as the compound (A) represented by formula(VII), a compound of the following formula (I) is preferable:

wherein R¹, R² and X are the same as those previously defined, providedthat when R¹ and R² are each a hydrogen atom, X is not —NHYHN— group inwhich Y represents C_(n)H_(2n−2) (in which n is an integer of 2 to 6),

(in which n is an integer of 2 to 6),

Specific examples of the compound represented by formula (I) are shownbelow.

TABLE 1 Compound No. Structure 1

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717 (not used) 718

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The aromatic carboxylic acid compounds represented by formula (I)according to the present invention are novel compounds. When thecompounds of formula (I) are used as the color developers in thethermosensitive recording material, the oil resistance, the plasticizerresistance and the heat resistance of an image area formed in therecording material are improved. The reason for this improvement has notbeen clarified, but it is considered that the following factors (1) to(4) contribute to the improvement of the preservation stability of therecorded image area:

(1) The affinity of the color developer for a leuco dye is increasedwhen an electron-donating group is present in the above-mentionedcompound of formula (I).

(2) When the compound of formula (I) has a substituent such as anelectron-attracting group, the compound becomes a strong acid, and thecolor development performance of the compound is improved.

(3) Since two or more aromatic carboxylic acid moieties are contained inone molecule of the color developer compound, the molecular weight isincreased, and therefore, the solubility of the color developer inplasticizers is decreased.

(4) Since two or more aromatic carboxylic acid moieties are contained inone molecule of the color developer compound, the molecule of the colordeveloper becomes so bulky as to surround a molecule of a leuco dyecompound.

The aromatic carboxylic acid compound of formula (I) can be produced inaccordance with the following reaction scheme:

wherein R¹, R² and X are the same as those previously defined.

In the present invention, an aromatic carboxylic acid compound offormula (I′) can be produced by allowing a nitrophthalic anhydride offormula (II) to react with a compound of formula (III):

wherein Y is an alkylene group having 2 to 12 carbon atoms, a xylylenegroup,

wherein X is —NHYHN— group in which Y is the same as that previouslydefined.

Further, there is provided a method of producing an aromatic carboxylicacid compound of formula (V):

wherein Y is the same as that previously defined, comprising the step ofallowing 3-nitrophthalic anhydride to react with a diamine compound offormula (IV) using a reaction solvent selected from the group consistingof acetic acid, tetrahydrofuran and nitrobenzene:

H₂N—Y—NH₂  (IV)

wherein Y is the same as that previously defined.

By the above-mentioned synthesis method, the aromatic carboxylic acidcompound of formula (V), that is, a 3-nitrophthalamide dimer, can beefficiently produced as a pure product.

In addition, there is also provided a method of producing an aromaticcarboxylic acid compound of formula (VI), which method comprises thesteps of dissolving 3-nitrophthalic anhydride in acetic anhydride toprepare an acetic anhydride solution of 3-nitrophthalic anhydride, andadding a diamine compound (H₂N—Y—NH₂) in small portions to the aceticanhydride solution so as to dissolve the diamine compound therein:

wherein Y is the same as that previously defined.

In this case, although the aromatic carboxylic acid compound of formula(VI) can be efficiently produced in relatively high yields, a traceamount of the compound represented by formula (V) is simultaneouslygenerated as the by-product.

To obtain the compound of formula (VI) in a pure product, the followingseparating and purification step is effective. Namely, the compound offormula (VI) can be preferentially extracted from a mixture of thereaction products, namely, the aromatic carboxylic acid compounds offormulas (V) and (VI) with a mixed solvent of water and an alcohol. Inthe present invention, ethyl alcohol is preferably used for thepreparation of the mixed solvent. In such a case, it is preferable thatthe ratio by volume of water to ethyl alcohol for use in the mixedsolvent be in the range of 60:40 to 70:30.

Thus, the aromatic carboxylic acid compounds of formulas (V) and (VI)can be selectively and efficiently synthesized from the reaction between3-nitrophthalic anhydride and a diamine compound.

As the leuco dye for use in the present invention, which may be employedalone or in combination, any conventional dyes for use in theconventional leuco-dye-containing recording materials can be employed.For example, triphenylmethanephthalide leuco compounds, triallylmethaneleuco compounds, fluoran leuco compounds, phenothiazine leuco compounds,thiofluoran leuco compounds, xanthene leuco compounds, indophthalylleuco compounds, spiropyran leuco compounds, azaphthalide leucocompounds, couromeno-pyrazole leuco compounds, methine leuco compounds,rhodamineanilino-lactam leuco compounds, rhodaminelactam leucocompounds, quinazoline leuco compounds, diazaxanthene leuco compoundsand bislactone leuco compounds are preferably employed.

Specific examples of those leuco dyes are as follows:

3,3-bis(p-dimethylanilino)phthalide,

3,3-bis(p-dimethylanilino)-6-dimethylaminophthalide (or Crystal VioletLactone),

3,3-bis(p-dimethylanilino)-6-diethylaminophthalide,

3,3-bis(p-dimethylanilino)-6-chlorophthalide,

3,3-bis(p-dibutylanilino)phthalide,

3-cyclohexylamino-6-chlorofluoran,

3-dimethylamino-5,7-dimethylfluoran,

3-diethylamino-7-chlorofluoran,

3-diethylamino-7-methylfluoran,

3-diethylamino-7,8-benzfluoran,

3-diethylamino-6-methyl-7-chlorofluoran,

3-(N-p-tolyl-N-ethylamino)-6-methyl-7-anilinofluoran,

3-pyrrolidino-6-methyl-7-anilinofluoran,

2-(m-trifluoromethylanilino)-6-diethylaminofluoran,

2-[3,6-bis(diethylamino)-9-(o-chloroanilino)xanthylbenzoic acid lactam],

3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran,

3-diethylamino-7-(o-chloroanilino)fluoran,

3-dibutylamino-7-(o-chloroanilino)fluoran,

3-diamylamino-6-methyl-7-anilinofluoran,

3-(N-methyl-N-amylamino)-6-methyl-7-anilinofluoran,

3-(N-methyl-N-isopropylamino)-6-methyl-7-anilinofluoran,

3-(N-methyl-N-cyclohexylamino)-6-methyl-7-anilinofluoran,

3-(N-ethyl-N-isopropylamino)-6-methyl-7-anilinofluoran,

3-(N-methyl-N-isoamylamino)-6-methyl-7-anilinofluoran,

3-(N-methyl-N-isobutylamino)-6-methyl-7-anilinofluoran,

3-diethylamino-6-chloro-7-anilinofluoran,

3-(N-ethyl-N-2-ethoxypropylamino)-6-methyl-7-anilinofluoran,

3-(N-ethyl-N-tetrafurfurylamino)-6-methyl-7-anilinofluoran,

3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluoran,

3-diethylamino-6-methyl-7-anilinofluoran,

3-dibutylamino-6-methyl-7-anilinofluoran,

3-diethylamino-5-methyl-7-(N,N-dibenzylamino)-fluoran,

benzoyl leuco methylene blue,

6′-chloro-8′-methoxy-benzoindolino-spiropyran,

6′-bromo-8′-methoxy-benzoindolino-spiropyran,

3-(2′-hydroxy-4′-dimethylanilino)-3-(2′-methoxy-5′-chlorophenyl)phthalide,

3-(2′-hydroxy-4′-dimethylanilino)-3-(2′-methoxy-5′-nitrophenyl)phthalide,

3-(2′-hydroxy-4′-diethylanilino)-3-(2′-methoxy-5′-tolyl)phthalide,

3-diethylamino-6-methyl-7-(2′,4′-dimethylanilino)-fluoran,

3-(2′-methoxy-4′-dimethylanilino)-3-(2′-hydroxy-4′-chloro-5′-tolyl)phthalide,

3-morphorino-7-(N-propyl-trifluoromethylanilino)-fluoran,

3-pyrrolidino-7-trifluoromethylanilinofluoran,

3-diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluoran,

3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluoran,

3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran,

3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluoran,

3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran,

3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran,

3-diethylamino-7-piperidinofluoran,

2-chloro-3-(N-methyltoluidino)-7-(p-N-butylanilino)fluoran,

3-(N-ethyl-N-cyclohexylamino)-5,6-benzo-7-α-naphthylamino-4′-bromofluoran,

3-(N-benzyl-N-cyclohexylamino)-5,6-benzo-7-α-naphthylamino-4′-bromofluoran,

3-diethylamino-6-methyl-7-mesidino-4′,5′-benzofluoran,

3-(p-dimethylanilino)-3-[1,1-bis(p-dimethylanilino)ethylene-2-yl]phthalide,

3-(p-dimethylanilino)-3-[1,1-bis(p-dimethylanilino)ethylene-2-yl]-6-dimethylaminophthalide,

3-(p-dimethylanilino)-3-(1-p-dimethylanilino-1-phenylethylene-2-yl)phthalide,

3-(p-dimethylanilino)-3-(1-p-dimethylanilino-1-p-chlorophenylethylene-2-yl)-6-dimethylaminophthalide,

3-(4′-dimethylamino-2′-methoxy)-3-(1″-p-dimethylanilino-1″-p-chlorophenyl-1″,3″-butadiene-4″-yl)benzophthalide,

3-(4′-dimethylamino-2′-benzyloxy)-3-(1″-p-dimethylanilino-1″-phenyl-1″,3″-butadiene-4″-yl)benzophthalide,

3,6-bis(dimethylamino)fluorenespiro(9,3′)-6″-dimethylaminophthalide,

3-dimethylamino-6-dimethylamino-fluorene-9-spiro-3′-(6′-dimethylamino)phthalide,

3,3-bis[2-(p-dimethylanilino)-2-(p-methoxyphenyl)ethenyl]-4,5,6,7-tetrachlorophthalide,

3-bis[1,1-bis(4-pyrrolidinophenyl)ethylene-2-yl]-5,6-dichloro-4,7-dibromophthalide,

bis(p-dimethylaminostyryl)-1-naphthalenesulfonylmethane, and

bis(p-dimethylaminostyryl)-1-p-tolylsulfonylmethane.

The thermosensitive coloring layer comprises the above-mentioned leucodye serving as the coloring agent, and the previously mentioned compound(A), preferably the aromatic carboxylic acid compound of formula (I),serving as the color developer. When necessary, variouselectron-acceptor compounds, for example, phenol compounds, thiophenolcompounds, thiourea derivatives, organic acids and metallic saltsthereof may be used in combination with the aforementioned compound (A).

Specific examples of the color developer for use in the presentinvention are as follows:

4,4′-isopropylidenebisphenol,

4,4′-isopropylidenebis(o-cresol),

4,4′-sec-butylidenebisphenol,

4,4′-isopropylidenebis(o-tert-butylphenol),

4,4′-cyclohexylidenebisphenol,

4,4′-isopropylidenebis(2-chlorophenol),

2,2′-methylenebis(4-methyl-6-tert-butylphenol),

2,2′-methylenebis(4-ethyl-6-tert-butylphenol),

4,4′-sec-butylidenebis(6-tert-butyl-2-cresol),

1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane,

4,4′-thiobis(6-tert-butyl-2-cresol),

2,4′-diphenolsulfone,

2,2′-diallyl-4,4′-dihydroxydiphenylsulfone,

3,4′-dihydroxy-4′-methyldiphenylsulfone,

4-isopropoxy-4′-hydroxydiphenylsulfone,

4-benzyloxy-4′-hydroxydiphenylsulfone,

4,4′-diphenolsulfoxide,

isopropyl p-hydroxybenzoate,

benzyl p-hydroxybenzoate,

benzyl protocatechuate,

stearyl gallate,

lauryl gallate,

octyl gallate,

1,7-bis(4-hydroxyphenylthio)-3,5-dioxaheptane,

1,5-bis(4-hydroxyphenylthio)-3-oxapentane,

1,3-bis(4-hydroxyphenylthio)-propane,

monocalcium salt of monobenzyl phthalate,

N,N′-diphenylthiourea,

N,N′-di(m-chlorophenyl)thiourea,

salicylanilide,

antipyrine complex of zinc thiocyanate,

zinc salt of 1-acetyloxy-2-naphthoic acid,

zinc salt of 2-acetyloxy-3-naphthoic acid,

zinc salt of 2-acetyloxy-1-naphthoic acid,

bis(4-hydroxyphenyl)methyl acetate,

bis(4-hydroxyphenyl)benzyl acetate,

4-[β-(p-methoxyphenoxy)ethoxy]salicylic acid,

1,3-bis(4-hydroxyphenyl)benzene,

1,4-bis(4-hydroxyphenyl)benzene,

4,4′-diphenolsulfone,

3,3′-diallyl-4,4′-diphenolsulfone,

α,α-bis(4-hydroxyphenyl)-α-methyltoluene,

tetrabromobisphenol A,

tetrabromobisphenol S,

4,4′-thiobis(2-methylphenol),

4,4′-thiobis(2-chlorophenol),

zinc p-nitrobenzoate,

1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid,

2,2-bis(3,4′-dihydroxyphenyl)propane, and

bis(4-hydroxy-3-methylphenyl)sulfide.

To obtain a thermosensitive recording material according to the presentinvention, the thermosensitive coloring layer comprising theabove-mentioned leuco dyes and color developers, and auxiliarycomponents to be described later may be provided on the support.

The thermosensitive coloring layer may further comprise a binder agent.As the binder agent for use in the present invention, any conventionalbinder agents used in the conventional thermosensitive recordingmaterials can appropriately be employed.

Examples of the binder agent for use in the thermosensitive coloringlayer include water-soluble polymers such as polyvinyl alcohol, starchand starch derivatives, cellulose derivatives such as methoxy cellulose,hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose andethyl cellulose, sodium polyacrylate, polyvinyl pyrrolidone,acrylamide-acrylic ester copolymer, acrylamide-acrylic ester-methacrylicacid terpolymer, alkali salts of styrene-maleic anhydride copolymer,alkali salts of isobutylene-maleic anhydride copolymer, polyacrylamide,sodium alginate, gelatin, and casein; emulsions such as polyvinylacetate, polyurethane, polyacrylate, polymethacrylate, vinylchloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer,vinyl acetate-acryl copolymer and styrene-acrylic ester copolymer; andlatexes such as styrene-butadiene copolymer and styrene-butadiene-acrylcopolymer.

According to the present invention, the thermosensitive coloring layermay further comprise a thermofusible material as thethermosensitivity-improving agent.

Specific examples of the thermofusible material are as follows: fattyacids such as stearic acid and behenic acid; fatty amides such asstearamide and palmitamide; fatty acid metallic salts such as zincstearate, aluminum stearate, calcium stearate, zinc palmitate, and zincbehenate; and diphenyl sulfone, diphenyl methane, p-benzylbiphenyl,terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl1-hydroxy-2-naphthoate, diphenyl carbonate, guaiacol carbonate, dibenzylterephithalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene,1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene,1,2-bis(phenoxy)ethane, 1,2-bis(3-methylphenoxy)ethane,1,2-bis(4-methylphenoxy)ethane, 1,4-bis(phenoxy)butane,1,4-bis(phenoxy)-2-butene, 1,2-bis(4-(methoxyphenylthio)ethane,dibenzoylmnethane, 1,4-bis(phenylthio)butane,1,4-bis(phenylthio)-2-butene, 1,2-bis(4-methoxyphenylthio)ethane,1,3-bis(2-vinyloxyethoxy)benzene, 1,4-bis(2-vinyloxyethoxy)benzene,p-(2-vinyloxyethoxy)biphenyl, p-aryloxybiphenyl, p-propargyloxybiphenyl,dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyl disulfide,1,1-diphenylethanol, 1,1-diphenylpropanol, p-(benzyloxy)benzyl alcohol,1,3-diphenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene,N-octadecylcarbamoylbenzene, dibenzyl oxalate,bis(4-methylbenzyl)oxalate, bis(4-chlorobenzyl)oxalate,1,5-bis(p-methoxyphenyloxy)-3-oxapentane, and1,2-bis(4-methoxyphenoxy)propane.

When necessary, the thermosensitive coloring layer may further compriseauxiliary additive components such as a filler, a surface active agent,a lubricant and an agent for preventing color formation by pressureapplication, which are used in the conventional thermosensitiverecording materials.

Examples of the filler for use in the present invention arefinely-divided particles of inorganic fillers such as calcium carbonate,silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide,barium sulfate, clay, kaolin, talc, surface-treated calcium andsurface-treated silica; and finely-divided particles of organic fillerssuch as urea-formaldehyde resin, styrene-methacrylic acid copolymer,polystyrene resin and vinylidene chloride resin.

Examples of the lubricant for use in the present invention includehigher fatty acids and amides, esters and metallic salts thereof; and avariety of waxes such as an animal wax, a vegetable wax, a mineral wax,and a petroleum wax.

When the thermosensitive coloring layer coating liquid comprising thecompound (A) is coated and dried to provide the thermosensitive coloringlayer, it is proper that the content of compound (A) serving as thecolor developer, for example, the aromatic carboxylic acid compound offormula (I), be in the range of 1 to 5 g/m², preferably 1 to 2 g/m² on adry basis.

It is preferable that the thermosensitive recording material of thepresent invention further comprise an intermediate layer comprising asthe main component plastic void particles in the form of sphere, whichis provided between the support and the thermosensitive coloring layer.This intermediate layer serves as a heat-insulating layer. Owing to theintermediate layer, therefore, thermal energy supplied by a thermal headcan efficiently be utilized, thereby improving the thermosensitivity ofthe recording material.

In particular, when the average particle diameter of the plastic voidparticles for use in the intermediate layer is in the range of 0.2 to 20μm and the voidage thereof is 40% or more, the flexibility of theintermediate layer is increased. As a result, the adhesion between thethermosensitive recording material and the thermal head is improved, andtherefore, dot reproduction performance becomes excellent.

The void particles for use in the intermediate layer comprise athermoplastic resin for forming a shell of each void particle. Air orother gasses are contained in the void particles in the expanded state.

It is preferable that the average particle diameter of the voidparticles be in the range of about 0.2 to 20 μm, as mentioned above.When the particle size of the void particles is within the above range,there is no problem in the production of the intermediate layer becausethe voidage of the void particles can freely be determined. In addition,the surface smoothness of the intermediate layer is not decreased aftercoating and drying the liquid comprising the void particles, so that theadhesion of the thermosensitive coloring layer to the thermal head doesnot lower, and consequently, deterioration of the thermosensitivity ofthe recording material can be avoided. Further, it is preferable thatthe void particles classified in a narrow distribution be employed inthe intermediate layer.

It is preferable that the voidage of the void particles for use in theintermediate layer be 40% or more, and more preferably 90% or more, fromthe viewpoint of the heat insulating effect. In the present invention,the voidage of the void particles for use in the intermediate layer isexpressed by the following formula:${{Voidage}\quad (\%)} = {\frac{\left( {{Inner}\quad {diameter}\quad {of}\quad {void}\quad {particle}} \right)}{\left( {{Outer}\quad {diameter}\quad {of}\quad {void}\quad {particle}} \right)} \times 100}$

When the voidage is within the above range, sufficient heat insulatingeffect of the intermediate layer can be obtained, so that the thermalenergy supplied by the thermal head can be inhibited from escapingthrough the support of the thermosensitive recording material. As aresult, the thermosensitivity-improving effect can be increased.

Specific examples of the thermoplastic resin for forming a shell of thevoid particle are polystyrene, polyvinyl chloride, polyvinylidenechloride, polyvinyl acetate, polyacrylate, polyacrylonitrile,polybutadiene, and copolymer resin thereof. Of those thermoplasticresins, a copolymer resin comprising as the main component vinylidenechloride or acrylonitrile is preferably employed in the presentinvention.

A binder resin for the formation of the above-mentioned intermediatelayer may be appropriately selected from the conventional water-solublepolymers and aqueous polymeric emulsions.

Specific examples of the binder agent for use in the intermediate layerinclude water-soluble polymers such as polyvinyl alcohol, starch andstarch derivatives, cellulose derivatives such as methoxy cellulose,hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose andethyl cellulose, sodium polyacrylate, polyvinyl pyrrolidone,acrylamide-acrylic ester copolymer, acrylamide-acrylic ester-methacrylicacid terpolymer, alkali salts of styrene-maleic anhydride copolymer,alkali salts of isobutylene-maleic anhydride copolymer, polyacrylamide,sodium alginate, gelatin, and casein; and aqueous polymeric emulsions,for example, latexes such as styrene-butadiene copolymer andstyrene-butadiene-acryl copolymer and emulsions such as vinyl acetateresin, vinyl acetate-acrylic acid copolymer, styrene-acrylic estercopolymer, acrylate resin, and polyurethane resin.

In the intermediate layer for use in the present invention, thepreviously mentioned minute void particles and binder resin may be usedin combination with auxiliary additive components such as a filler, athermofusible material and a surface active agent, which are used in theconventional thermosensitive recording materials. Specific examples ofthe filler and the thermofusible material are the same as thosementioned in the description of the thermosensitive coloring layer.

Furthermore, in the present invention, an additional layer comprising apigment, a binder agent and a thermofusible material may be interposedbetween the intermediate layer and the thermosensitive coloring layerwhen necessary.

In addition, the thermosensitive recording material may further comprisea protective layer which is formed on the thermosensitive coloring layerin order to improve the head-matching properties of the thermosensitiverecording material with the thermal head, improve the preservationstability of the recorded images and improve the writing and printingquality of the recording material. In this case, the protective layercomprises the previously mentioned filler, binder resin andthermofusible material.

The thermosensitive recording material of the present invention isusable in any fields that employ the conventional thermosensitiverecording materials. For instance, the thermosensitive recordingmaterial can be used as a paper for facsimile apparatus, apoint-of-sales (POS) label for food, a bar code label for industrialapplications, a thermosensitive recording adhesive label of liner-lesstype, a ticket paper, a magnetic ticket paper, a paper for CAD, and atransparent thermosensitive film.

Other features of this invention will become apparent in the course ofthe following description of exemplary embodiments, which are given forillustration of the invention and are not intended to be limitingthereof.

EXAMPLE 1

A mixture of the following components was separately dispersed andpulverized in a porcelain ball mill, so that a Liquid A, a Liquid B, aLiquid C and a Liquid D were prepared:

Parts by Weight [Liquid A] 10 3-N,N-dibutylamino-6-methyl-7-anilinofluoran 10% aqueous solution of 10 polyvinyl alcoholWater 30 [Liquid B] Compound No. 4 (shown in 10 TABLE 1) 10% aqueoussolution of 10 polyvinyl alcohol Water 30 [Liquid C] Silica gel 10(Trademark “P527” made by Mizusawa Industrial Chemicals, Ltd.) 10%aqueous solution of 10 polyvinyl alcohol Water 30 [Liquid D] Zincstearate 10 10% aqueous solution of 10 polyvinyl alcohol Water 30

A mixture of the following components was stirred and dispersed in adispersion mixer, so that a Liquid E was prepared:

[Liquid E] Parts by Weight Unexpanded minute void plastic particles 40(solid content: 24 wt. %, average particle diameter: 3 μm, and voidage:95%) Styrene - butadiene copolymer latex 10 Water 50

[Formation of intermediate layer]

The Liquid E and the Liquid C were mixed at a ratio by weight of 2:1, sothat a coating liquid for an intermediate layer was prepared. The thusprepared intermediate layer coating liquid was coated on a sheet ofcommercially available high quality paper with a basis weight of 60g/m², serving as a support, and then dried so as to have a depositionamount of 3 g/m² on a dry basis, whereby an intermediate layer wasformed on the support.

[Formation of thermosensitive coloring layer]

The Liquid A, the Liquid B, the Liquid C, and the Liquid D were mixed ata ratio by weight of 1:2:1:1 to prepare a thermosensitive coloring layercoating liquid. The thus prepared thermosensitive coloring layer coatingliquid was coated on the above prepared intermediate layer and thendried so as to have a deposition amount of 2.5 g/m² on a dry basis,whereby a thermosensitive coloring layer was formed on the intermediatelayer.

The surface of the thermosensitive coloring layer thus obtained wassubjected to calendering with the application of a pressure of 10kg/cm².

Thus, a thermosensitive recording material No. 1 according to thepresent invention was obtained.

EXAMPLE 2

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 5 shown in TABLE 1.

Thus, a thermosensitive recording material No. 2 according to thepresent invention was obtained.

EXAMPLE 3

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 6 shown in TABLE 1.

Thus, a thermosensitive recording material No. 3 according to thepresent invention was obtained.

EXAMPLE 4

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 15 shown in TABLE 1.

Thus, a thermosensitive recording material No. 4 according to thepresent invention was obtained.

EXAMPLE 5

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 27 shown in TABLE 1.

Thus, a thermosensitive recording material No. 5 according to thepresent invention was obtained.

EXAMPLE 6

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 55 shown in TABLE 1.

Thus, a thermosensitive recording material No. 6 according to thepresent invention was obtained.

EXAMPLE 7

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 11 shown in TABLE 1.

Thus, a thermosensitive recording material No. 7 according to thepresent invention was obtained.

EXAMPLE 8

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 12 shown in TABLE 1.

Thus, a thermosensitive recording material No. 8 according to thepresent invention was obtained.

EXAMPLE 9

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 13 shown in TABLE 1.

Thus, a thermosensitive recording material No. 9 according to thepresent invention was obtained.

EXAMPLE 10

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 14 shown in TABLE 1.

Thus, a thermosensitive recording material No. 10 according to thepresent invention was obtained.

EXAMPLE 11

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 22 shown in TABLE 1.

Thus, a thermosensitive recording material No. 11 according to thepresent invention was obtained.

EXAMPLE 12

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 23 shown in TABLE 1.

Thus, a thermosensitive recording material No. 12 according to thepresent invention was obtained.

EXAMPLE 13

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 24 shown in TABLE 1.

Thus, a thermosensitive recording material No. 13 according to thepresent invention was obtained.

EXAMPLE 14

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 26 shown in TABLE 1.

Thus, a thermosensitive recording material No. 14 according to thepresent invention was obtained.

EXAMPLE 15

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 50 shown in TABLE 1.

Thus, a thermosensitive recording material No. 15 according to thepresent invention was obtained.

EXAMPLE 16

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 51 shown in TABLE 1.

Thus, a thermosensitive recording material No. 16 according to thepresent invention was obtained.

EXAMPLE 17

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 54 shown in TABLE 1.

Thus, a thermosensitive recording material No. 17 according to thepresent invention was obtained.

EXAMPLE 18

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 56 shown in TABLE 1.

Thus, a thermosensitive recording material No. 18 according to thepresent invention was obtained.

EXAMPLE 19

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the intermediate layeremployed in Example 1 was not interposed between the support and thethermosensitive coloring layer.

Thus, a thermosensitive recording material No. 19 according to thepresent invention was obtained.

EXAMPLE 20

The procedure for preparation of the thermosensitive recording materialNo. 5 in Example 5 was repeated except that the intermediate layeremployed in Example 5 was not interposed between the support and thethermosensitive coloring layer.

Thus, a thermosensitive recording material No. 20 according to thepresent invention was obtained.

Comparative Example 1

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by mono-α-methyl 3-nitrophthalate.

Thus, a comparative thermosensitive recording material No. 1 wasobtained.

Comparative Example 2

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by mono-β-methyl 3-nitrophthalate.

Thus, a comparative thermosensitive recording material No. 2 wasobtained.

Comparative Example 3

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by mono-β-benzyl 3-nitrophthalate.

Thus, a comparative thermosensitive recording material No. 3 wasobtained.

Comparative Example 4

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by 2,4-hydroxyphenylsulfone.

Thus, a comparative thermosensitive recording material No. 4 wasobtained.

(Measurement of-Coloring Density of Image)

Each of the thermosensitive recording materials Nos. 1 to 20 accordingto the present invention obtained in Examples 1 to 20 and thecomparative thermosensitive recording materials Nos. 1 to 4 obtained inComparative Examples 1 to 4 was loaded in a printing test apparatusequipped with a commercially available thin film head (made byMatsushita Electronic Components Co., Ltd.), and images were formed oneach recording material under the conditions that the applied electricpower was 0.68 W/dot, the period for one line was 10 ms/line and thescanning line density was 8×3.85 dot/mm, with the pulse width changed to0.8 msec, 1.0 msec and 1.2 msec.

The coloring density of the recorded image was measured by a McBethdensitometer.

The results are given in TABLE 2.

(Evaluation of Preservation Stability of Recorded Image)

1. Plasticizer Resistance Test

Images were thermally printed on each of the thermosensitive recordingmaterials in such a manner that a heating block of 180° C. was broughtinto contact with each recording material for one second with theapplication of a pressure of 2 kg/cm² thereto, using a heat gradienttester made by TOYO SEIKI SEISAKU-SHO, Ltd.

The initial coloring density of each image area was measured using theMcBeth densitometer.

A sheet of commercially available polyvinyl chloride wrap, made byShin-Etsu Polymer Co., Ltd., was overlaid on the image area of eachimage-bearing sample. Each sample was allowed to stand at 40° C. withthe application of a load of 5 kg thereto for 16 hours.

After 16 hours, the density of the image area was measured using theMcBeth densitometer.

The results are shown in TABLE 2.

TABLE 2 Preservation Stability of Recorded Image (Coloring Density)Coloring Density At initial Plasticizer 0.8 ms 1.0 ms 1.2 ms stageresistance test Ex. 1 1.30 1.30 1.31 1.45 0.80 Ex. 2 1.25 1.33 1.33 1.460.70 Ex. 3 1.28 1.29 1.32 1.45 0.72 Ex. 4 1.18 1.30 1.32 1.23 0.69 Ex. 50.96 1.07 1.08 1.18 1.13 Ex. 6 0.85 1.03 1.00 1.15 1.02 Ex. 7 1.28 1.301.32 1.40 0.82 Ex. 8 1.30 1.31 1.30 1.42 0.85 Ex. 9 1.31 1.31 1.31 1.450.81 Ex. 10 1.30 1.31 1.31 1.40 0.90 Ex. 11 1.25 1.30 1.31 1.35 1.00 Ex.12 1.28 1.31 1.33 1.40 0.99 Ex. 13 1.00 1.10 1.11 1.25 1.20 Ex. 14 1.011.08 1.12 1.15 1.10 Ex. 15 1.20 1.25 1.28 1.35 1.10 Ex. 16 1.15 1.201.22 1.33 1.08 Ex. 17 0.90 1.10 1.12 1.20 1.13 Ex. 18 0.80 0.99 1.081.18 1.15 Ex. 19 0.59 0.99 1.21 1.48 0.75 Ex. 20 0.51 0.83 0.95 1.171.07 Comp. 1.20 1.31 1.33 1.41 0.46 Ex. 1 Comp. 1.29 1.35 1.36 1.44 0.50Ex. 2 Comp. 1.10 1.21 1.30 1.35 0.55 Ex. 3 Comp. 1.24 1.36 1.35 1.600.35 Ex. 4

As can be seen from the results shown in TABLE 2, the plasticizerresistance of images formed in the thermosensitive recording material ofthe present invention is excellent. In addition, when the intermediatelayer comprising minute void particles is interposed between the supportand the thermosensitive coloring layer, the coloring sensitivity isimproved and the plasticizer resistance is excellent.

EXAMPLE 21

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 123 shown in TABLE 1.

Thus, a thermosensitive recording material No. 21 according to thepresent invention was obtained.

EXAMPLE 22

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 131 shown in TABLE 1.

Thus, a thermosensitive recording material No. 22 according to thepresent invention was obtained.

EXAMPLE 23

The procedure for preparation of the thermosensitive recording materialNo. 21 in Example 21 was repeated except that the intermediate layeremployed in Example 21 was not interposed between the support and thethermosensitive coloring layer.

Thus, a thermosensitive recording material No. 23 according to thepresent invention was obtained.

EXAMPLE 24

The procedure for preparation of the thermosensitive recording materialNo. 22 in Example 22 was repeated except that the intermediate layeremployed in Example 22 was not interposed between the support and thethermosensitive coloring layer.

Thus, a thermosensitive recording material No. 24 according to thepresent invention was obtained.

Comparative Example 5

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by 2,4′-dihydroxydiphenylsulfone.

Thus, a comparative thermosensitive recording material No. 5 wasobtained.

Comparative Example 6

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by the following compound:

Thus, a comparative thermosensitive recording material No. 6 wasobtained.

Comparative Example 7

The procedure for preparation of the comparative thermosensitiverecording material No. 6 in Comparative Example 6 was repeated exceptthat the intermediate layer employed in Comparative Example 6 was notinterposed between the support and the thermosensitive coloring layer.

Thus, a comparative thermosensitive recording material No. 7 wasobtained.

(Measurement of Coloring Density of Image)

Each of the thermosensitive recording materials Nos. 21 to 24 accordingto the present invention obtained in Examples 21 to 24 and thecomparative thermosensitive recording materials Nos. 5 to 7 obtained inComparative Examples 5 to 7 was loaded in a printing test apparatusequipped with a commercially available thin film head (made byMatsushita Electronic Components Co., Ltd.), and images were formed oneach recording material under the conditions that the applied electricpower was 0.68 W/dot, the period for one line was 10 ms/line and thescanning line density was 8×3.85 dot/mm, with the pulse width changed to0.8 msec, 1.0 msec and 1.2 msec.

The coloring density of the recorded image was measured by a McBethdensitometer.

The results are given in TABLE 3.

(Evaluation of Preservation Stability of Recorded Image)

1. Oil Resistance Test

Images were thermally printed on each of the thermosensitive recordingmaterials in such a manner that a heating block of which temperature wasset to a temperature where the image recorded in the recording materialshowed a saturation coloring density was brought into contact with eachrecording material for one second with the application of a pressure of2 kg/cm² thereto, using a heat gradient tester made by TOYO SEIKISEISAKU-SHO, Ltd.

The initial coloring density of each image area was measured using theMcBeth densitometer.

A cotton seed oil was applied to the image area of each image-bearingsample. Each sample was allowed to stand at 40° C. for 16 hours.

After 16 hours, the density of the image area was measured to evaluatethe oil resistance.

The results are also shown in TABLE 3.

2. Heat Resistance Test

Images were thermally printed on each of the thermosensitive recordingmaterials in such a manner that a heating block of which temperature wasset to a temperature where the image recorded in the recording materialshowed a saturation coloring density was brought into contact with eachrecording material for one second with the application of a pressure of2 kg/cm² thereto, using a heat gradient tester made by TOYO SEIKISEISAKU-SHO, Ltd.

Each image-bearing sample was allowed to stand at 100° C. for 15 hours.After 15 hours, the density of the image area was measured to evaluatethe heat resistance.

The results are also shown in TABLE 3.

TABLE 3 Preservation Stability of Recorded Image (Coloring Density) AtOil Heat Coloring Density initial resistance resistance 0.8 ms 1.0 ms1.2 ms stage test test Ex. 21 1.11 1.10 1.01 1.25 1.16 0.92 Ex. 22 1.101.13 1.09 1.24 1.21 0.92 Ex. 23 0.62 0.77 0.83 1.01 0.82 0.82 Ex. 240.67 0.82 0.93 1.06 0.92 0.80 Comp. 1.36 1.39 1.38 1.55 0.80 0.88 Ex. 5Comp. 0.91 1.10 1.08 1.22 1.04 0.65 Ex. 6 Comp. 0.65 0.75 0.82 1.07 0.890.40 Ex. 7

As can be seen from the results shown in TABLE 3, the oil resistance andthe heat resistance of images formed in the thermosensitive recordingmaterial of the present invention are excellent.

EXAMPLE 25

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 175 shown in TABLE 1.

Thus, a thermosensitive recording material No. 25 according to thepresent invention was obtained.

EXAMPLE 26

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 187 shown in TABLE 1.

Thus, a thermosensitive recording material No. 26 according to thepresent invention was obtained.

EXAMPLE 27

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 193 shown in TABLE 1.

Thus, a thermosensitive recording material No. 27 according to thepresent invention was obtained.

EXAMPLE 28

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 180 shown in TABLE 1.

Thus, a thermosensitive recording material No. 28 according to thepresent invention was obtained.

EXAMPLE 29

The procedure for preparation of the thermosensitive recording materialNo. 25 in Example 25 was repeated except that the intermediate layeremployed in Example 25 was not interposed between the support and thethermosensitive coloring layer.

Thus, a thermosensitive recording material No. 29 according to thepresent invention was obtained.

EXAMPLE 30

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 199 shown in TABLE 1.

Thus, a thermosensitive recording material No. 30 according to thepresent invention was obtained.

EXAMPLE 31

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 205 shown in TABLE 1.

Thus, a thermosensitive recording material No. 31 according to thepresent invention was obtained.

EXAMPLE 32

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 211 shown in TABLE 1.

Thus, a thermosensitive recording material No. 32 according to thepresent invention was obtained.

EXAMPLE 33

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 529 shown in TABLE 1.

Thus, a thermosensitive recording material No. 33 according to thepresent invention was obtained.

EXAMPLE 34

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 523 shown in TABLE 1.

Thus, a thermosensitive recording material No. 34 according to thepresent invention was obtained.

EXAMPLE 35

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 522 shown in TABLE 1.

Thus, a thermosensitive recording material No. 35 according to thepresent invention was obtained.

EXAMPLE 36

The procedure for preparation of the thermosensitive recording materialNo. 33 in Example 33 was repeated except that the intermediate layeremployed in Example 33 was not interposed between the support and thethermosensitive coloring layer.

Thus, a thermosensitive recording material No. 36 according to thepresent invention was obtained.

EXAMPLE 37

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 521 shown in TABLE 1.

Thus, a thermosensitive recording material No. 37 according to thepresent invention was obtained.

EXAMPLE 38

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 528 shown in TABLE 1.

Thus, a thermosensitive recording material No. 38 according to thepresent invention was obtained.

EXAMPLE 39

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 676 shown in TABLE 1.

Thus, a thermosensitive recording material No. 39 according to thepresent invention was obtained.

EXAMPLE 40

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 689 shown in TABLE 1.

Thus, a thermosensitive recording material No. 40 according to thepresent invention was obtained.

EXAMPLE 41

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 681 shown in TABLE 1.

Thus, a thermosensitive recording material No. 41 according to thepresent invention was obtained.

EXAMPLE 42

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 694 shown in TABLE 1.

Thus, a thermosensitive recording material No. 42 according to thepresent invention was obtained.

EXAMPLE 43

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 686 shown in TABLE 1.

Thus, a thermosensitive recording material No. 43 according to thepresent invention was obtained.

EXAMPLE 44

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 699 shown in TABLE 1.

Thus, a thermosensitive recording material No. 44 according to thepresent invention was obtained.

EXAMPLE 45

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 702 shown in TABLE 1.

Thus, a thermosensitive recording material No. 45 according to thepresent invention was obtained.

EXAMPLE 46

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 715 shown in TABLE 1.

Thus, a thermosensitive recording material No. 46 according to thepresent invention was obtained.

EXAMPLE 47

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 707 shown in TABLE 1.

Thus, a thermosensitive recording material No. 47 according to thepresent invention was obtained.

EXAMPLE 48

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 721 shown in TABLE 1.

Thus, a thermosensitive recording material No. 48 according to thepresent invention was obtained.

EXAMPLE 49

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 712 shown in TABLE 1.

Thus, a thermosensitive recording material No. 49 according to thepresent invention was obtained.

EXAMPLE 50

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 726 shown in TABLE 1.

Thus, a thermosensitive recording material No. 50 according to thepresent invention was obtained.

EXAMPLE 51

The procedure for preparation of the thermosensitive recording materialNo. 39 in Example 39 was repeated except that the intermediate layeremployed in Example 39 was not interposed between the support and thethermosensitive coloring layer.

Thus, a thermosensitive recording material No. 51 according to thepresent invention was obtained.

Comparative Example 8

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by 2,4′-dihydroxydiphenylsulfone.

Thus, a comparative thermosensitive recording material No. 8 wasobtained.

Comparative Example 9

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by the following compound:

Thus, a comparative thermosensitive recording material No. 9 wasobtained.

Comparative Example 10

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by the following compound:

Thus, a comparative thermosensitive recording material No. 10 wasobtained.

Comparative Example 11

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by the following compound:

Thus, a comparative thermosensitive recording material No. 11 wasobtained.

(Measurement of Coloring Density of Image)

Each of the thermosensitive recording materials Nos. 25 to 51 accordingto the present invention obtained in Examples 25 to 51 and thecomparative thermosensitive recording materials Nos. 8 to 11 obtained inComparative Examples 8 to 11 was loaded in a printing test apparatusequipped with a commercially available thin film head (made byMatsushita Electronic Components Co., Ltd.), and images were formed oneach recording material under the conditions that the applied electricpower was 0.68 W/dot, the period for one line was 10 ms/line and thescanning line density was 8×3.85 dot/mm, with the pulse width changed to0.4 msec, 0.8 msec and 1.2 msec.

The coloring density of the recorded image was measured by a McBethdensitometer.

The results are given in TABLE 4.

(Evaluation of Preservation Stability of Recorded Image)

Images were thermally printed on each of the thermosensitive recordingmaterials in such a manner that a heating block of which temperature wasset to a temperature where the image recorded in the recording materialshowed a saturation coloring density was brought into contact with eachrecording material for one second with the application of a pressure of2 kg/cm² thereto, using a heat gradient tester made by TOYO SEIKISEISAKU-SHO, Ltd.

The initial coloring density of each image area was measured using theMcBeth densitometer.

Then, the plasticizer resistance, the oil resistance and the heatresistance of the image area were evaluated by the following methods.

1. Plasticizer Resistance Test

Three sheets of commercially available polyvinyl chloride wrap, made byShin-Etsu Polymer Co., Ltd., were overlaid on the image area of eachimage-bearing sample. Each sample was allowed to stand at 40° C. withthe application of a load of 5 kg thereto for 15 hours.

After 15 hours, the density of the image area was measured using theMcBeth densitometer.

The results are shown in TABLE 4.

2. Oil Resistance Test

A cotton seed oil was applied to the image area of each image-bearingsample. Each sample was allowed to stand at 40° C. for 15 hours.

After 15 hours, the density of the image area was measured to evaluatethe oil resistance.

The results are also shown in TABLE 4.

3. Heat Resistance Test

Each image-bearing sample was allowed to stand at 100° C. for 15 hours.After 15 hours, the density of the image area was measured to evaluatethe heat resistance.

The results are also shown in TABLE 4.

TABLE 4 Preservation Stability of Recorded Image (Coloring Density)Coloring Density At Plasticizer Oil Heat 0.4 0.8 1.2 initial resistanceresistance resistance ms ms ms stage test test test Ex. 25 0.15 0.951.16 1.11 1.03 1.13 1.11 Ex. 26 0.11 0.56 1.20 1.44 1.09 1.33 1.46 Ex.27 0.15 0.57 1.16 1.44 1.06 1.24 1.43 Ex. 28 0.14 0.87 1.09 1.06 0.911.04 1.06 Ex. 29 0.10 0.68 1.02 1.03 0.82 0.93 1.00 Ex. 30 0.16 0.621.05 1.07 0.90 0.93 0.95 Ex. 31 0.18 0.78 1.15 1.10 0.98 1.00 1.01 Ex.32 0.23 0.52 1.13 1.09 0.93 0.97 0.95 Ex. 33 0.28 1.11 1.00 1.29 1.191.16 1.01 Ex. 34 0.26 1.15 1.11 1.33 1.04 1.07 1.23 Ex. 35 0.29 1.130.90 1.29 0.97 1.03 0.82 Ex. 36 0.19 0.82 1.03 1.20 0.84 1.15 1.10 Ex.37 0.19 1.00 1.08 1.13 1.08 1.10 1.23 Ex. 38 0.13 0.82 1.22 1.27 1.091.18 1.31 Ex. 39 0.15 0.90 1.06 1.11 1.03 1.13 1.11 Ex. 40 0.17 0.861.02 1.02 1.04 1.03 0.98 Ex. 41 0.22 0.92 1.06 1.15 0.99 1.14 1.02 Ex.42 0.25 0.95 1.05 1.20 0.93 1.10 0.84 Ex. 43 0.10 0.68 1.02 1.03 0.820.93 1.00 Ex. 44 0.18 0.87 1.01 1.02 0.95 0.99 0.83 Ex. 45 0.31 1.001.12 1.24 1.16 1.21 0.92 Ex. 46 0.29 1.01 1.10 1.20 1.13 1.16 0.99 Ex.47 0.26 0.99 1.15 1.22 1.11 1.23 0.95 Ex. 48 0.28 1.00 1.18 1.23 1.091.22 0.93 Ex. 49 0.19 0.92 1.09 1.15 1.03 1.13 0.89 Ex. 50 0.22 0.961.10 1.16 1.00 1.13 0.90 Ex. 51 0.12 0.62 0.92 1.01 0.88 0.95 0.78 Comp.0.57 1.41 1.42 1.59 0.59 0.72 1.64 Ex. 8 Comp. 0.17 0.77 0.75 1.01 0.680.78 0.45 Ex. 9 Comp. 0.18 0.91 1.08 1.22 1.02 1.04 0.65 Ex. 10 Comp.0.14 0.63 0.99 0.91 0.52 0.64 0.57 Ex. 11

As can be seen from the results shown in TABLE 4, all the plasticizerresistance, the oil resistance and the heat resistance of the image areaformed in the thermosensitive recording material of the presentinvention are excellent. In addition, when the intermediate layercomprising minute void particles is interposed between the support andthe thermosensitive coloring layer, the coloring sensitivity is improvedand the preservation stability of the recorded image is excellent.

EXAMPLE 52

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 668 shown in TABLE 1.

Thus, a thermosensitive recording material No. 52 according to thepresent invention was obtained.

EXAMPLE 53

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 663 shown in TABLE 1.

Thus, a thermosensitive recording material No. 53 according to thepresent invention was obtained.

EXAMPLE 54

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 673 shown in TABLE 1.

Thus, a thermosensitive recording material No. 54 according to thepresent invention was obtained.

EXAMPLE 55

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by Compound No. 671 shown in TABLE 1.

Thus, a thermosensitive recording material No. 55 according to thepresent invention was obtained.

EXAMPLE 56

The procedure for preparation of the thermosensitive recording materialNo. 52 in Example 52 was repeated except that the intermediate layeremployed in Example 52 was not interposed between the support and thethermosensitive coloring layer.

Thus, a thermosensitive recording material No. 56 according to thepresent invention was obtained.

Comparative Example 12

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by 2,4′-dihydroxydiphenylsulfone.

Thus, a comparative thermosensitive recording material No. 12 wasobtained.

Comparative Example 13

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by the following compound:

Thus, a comparative thermosensitive recording material No. 13 wasobtained.

Comparative Example 14

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by the following compound:

Thus, a comparative thermosensitive recording material No. 14 wasobtained.

Comparative Example 15

The procedure for preparation of the thermosensitive recording materialNo. 1 in Example 1 was repeated except that the Compound No. 4 in theLiquid B for the thermosensitive coloring layer coating liquid inExample 1 was replaced by the following compound:

Thus, a comparative thermosensitive recording material No. 15 wasobtained.

(Measurement of Coloring Density of Image)

Each of the thermosensitive recording materials Nos. 52 to 56 accordingto the present invention obtained in Examples 52 to 56 and thecomparative thermosensitive recording materials Nos. 12 to 15 obtainedin Comparative Examples 12 to 15 was loaded in a printing test apparatusequipped with a commercially available thin film head (made byMatsushita Electronic Components Co., Ltd.), and images were formed oneach recording material under the conditions that the applied electricpower was 0.68 W/dot, the period for one line was 10 ms/line and thescanning line density was 8×3.85 dot/mm, with the pulse width changed to0.4 msec, 0.8 msec and 1.2 msec.

The coloring density of the recorded image was measured by a McBethdensitometer.

The results are given in TABLE 5.

(Evaluation of Preservation Stability of Recorded Image)

Images were thermally printed on each of the thermosensitive recordingmaterials in such a manner that a heating block of which temperature wasset to a temperature where the image recorded in the recording materialshowed a saturation coloring density was brought into contact with eachrecording material for one second with the application of a pressure of2 kg/cm² thereto, using a heat gradient tester made by TOYO SEIKISEISAKU-SHO, Ltd.

The initial coloring density of each image area was measured using theMcBeth densitometer.

Then, the plasticizer resistance and the water resistance of the imagearea on each image-bearing sample were evaluated by the followingmethods.

1. Plasticizer Resistance Test

Three sheets of commercially available polyvinyl chloride wrap, made byShin-Etsu Polymer Co., Ltd., were overlaid on the image area of eachimage-bearing sample. Each sample was allowed to stand at 40° C. withthe application of a load of 5 kg thereto for 15 hours.

After 15 hours, the density of the image area was measured using theMcBeth densitometer.

The results are shown in TABLE 5.

2. Water Resistance Test

Each image-bearing sample was immersed in water, and thereafter allowedto stand at room temperature for 15 hours.

After 15 hours, the density of the image area was measured to evaluatethe water resistance.

The results are also shown in TABLE 5.

TABLE 5 Preservation Stability of Recorded Image (Coloring Density) AtPlasticizer Water Coloring Density initial resistance resistance 0.4 ms0.8 ms 1.2 ms stage test test Ex. 52 0.23 0.92 1.04 1.09 0.93 0.88 Ex.53 0.14 0.86 1.05 1.01 0.99 0.91 Ex. 54 0.19 0.87 1.02 1.03 0.80 0.92Ex. 55 0.20 0.85 1.01 1.01 0.92 0.81 Ex. 56 0.15 0.66 0.82 0.82 0.760.75 Comp. 0.57 1.41 1.42 1.59 0.59 1.30 Ex. 12 Comp. 0.17 0.77 0.751.01 0.68 0.54 Ex. 13 Comp. 0.18 0.91 1.08 1.22 1.02 0.73 Ex. 14 Comp.0.14 0.63 0.99 0.91 0.52 0.76 Ex. 15

As can be seen from the results shown in TABLE 5, the plasticizerresistance and the water resistance of the image area formed in thethermosensitive recording material of the present invention areexcellent. In addition, when the intermediate layer comprising minutevoid particles is interposed between the support and the thermosensitivecoloring layer, the coloring sensitivity is improved and thepreservation stability of the recorded image is excellent.

Preparation Example 1

[Synthesis of Compound No. 1 shown in TABLE 1]

19.3 g of 3-nitrophthalic anhydride and 3.1 g of ethylene glycol weredispersed in 100 ml of toluene. This reaction mixture was refluxed for 5hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a white solid.

The white solid material thus obtained was dispersed in 600 ml of waterand heated to 80° C. Then, the mixture was stirred for 2 hours, andcooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 50% aqueoussolution of ethanol, thereby obtaining the Compound No. 1 as whitecrystals in a yield of 12.4 g.

The melting point of this compound was 240 to 243° C.

FIG. 1 is an infrared spectrum of the Compound No. 1.

Preparation Example 2

[Synthesis of Compound No. 3 shown in TABLE 1]

19.3 g of 3-nitrophthalic anhydride and 4.5 g of 1,4-butanediol weredispersed in 100 ml of toluene. This reaction mixture was refluxed for 5hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a white solid.

The white solid material thus obtained was dispersed in 600 ml of waterand heated to 80° C. Then, the mixture was stirred for 2 hours, andcooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 50% aqueoussolution of ethanol, thereby obtaining the Compound No. 3 as whitecrystals in a yield of 12.6 g.

The melting point of this compound was 205 to 207° C.

FIG. 2 is an infrared spectrum of the Compound No. 3.

Preparation Example 3

[Synthesis of Compound No. 4 shown in TABLE 1]

19.3 g of 3-nitrophthalic anhydride and 5.2 g of 1,5-pentanediol weredispersed in 100 ml of toluene. This reaction mixture was refluxed for 6hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a white solid.

The white solid material thus obtained was dispersed in 500 ml of waterand heated to 80° C. Then, the mixture was stirred for 2 hours, andcooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 50% aqueoussolution of ethanol, thereby obtaining the Compound No. 4 as whitecrystals in a yield of 12.1 g.

The melting point of this compound was 213 to 217° C.

FIG. 3 is an infrared spectrum of the Compound No. 4.

Preparation Example 4

[Synthesis of Compound No. 5 shown in TABLE 1]

19.3 g of 3-nitrophthalic anhydride and 5.9 g of 1,6-hexanediol weredispersed in 150 ml of toluene. This reaction mixture was refluxed for 6hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a white solid.

The white solid material thus obtained was dispersed in 500 ml of waterand heated to 80° C. Then, the mixture was stirred for 2 hours, andcooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 50% aqueoussolution of ethanol, thereby obtaining the Compound No. 5 as whitecrystals in a yield of 12.8 g.

The melting point of this compound was 211 to 214° C.

FIG. 4 is an infrared spectrum of the Compound No. 5.

Preparation Example 5

[Synthesis of Compound No. 6 shown in TABLE 1]

9.7 g of 3-nitrophthalic anhydride and 3.7 g of 1,8-octanediol weredispersed in 100 ml of toluene. This reaction mixture was refluxed for13 hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a white solid.

The white solid material thus obtained was dispersed in 800 ml of waterand heated to 80° C. Then, the mixture was stirred for 2 hours, andcooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 50% aqueoussolution of ethanol, thereby obtaining the Compound No. 6 as whitecrystals in a yield of 5.2 g.

The melting point of this compound was 168 to 171° C.

FIG. 5 is an infrared spectrum of the Compound No. 6.

Preparation Example 6

[Synthesis of Compound No. 10 shown in TABLE 1]

9.6 g of 3-nitrophthalic anhydride and 5.6 g of 1,12-dodecanediol weredispersed in 100 ml of toluene. This reaction mixture was refluxed for13 hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a yellow viscous material.

The yellow viscous material thus obtained was dispersed in 600 ml ofwater and heated to 80° C. Then, the mixture was stirred for 2 hours,and cooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 50% aqueoussolution of ethanol, thereby obtaining the Compound No. 10 as whitecrystals in a yield of 6.0 g.

The melting point of this compound was 105 to 110° C.

FIG. 6 is an infrared spectrum of the Compound No. 10.

Preparation Example 7

[Synthesis of Compound No. 11 shown in TABLE 1]

50.0 g of 3-nitrophthalic anhydride and 13.0 g of diethylene glycol weredispersed in 250 ml of toluene. This reaction mixture was refluxed for 5hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a white solid.

The white solid material thus obtained was dispersed in 1,000 ml ofwater and heated to 80° C. Then, the mixture was stirred for 2 hours,and cooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 30% aqueoussolution of ethanol, thereby obtaining the Compound No. 11 as whitecrystals in a yield of 41.0 g.

The melting point of this compound was 185 to 188° C.

FIG. 7 is an infrared spectrum of the Compound No. 11.

Preparation Example 8

[Synthesis of Compound No. 12 shown in TABLE 1]

50.0 g of 3-nitrophthalic anhydride and 19.0 g of triethylene glycolwere dispersed in 300 ml of toluene. This reaction mixture was refluxedfor 7 hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a white solid.

The white solid material thus obtained was dispersed in 1,000 ml ofwater and heated to 80° C. Then, the mixture was stirred for 2 hours,and cooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 50% aqueoussolution of ethanol, thereby obtaining the Compound No. 12 as whitecrystals in a yield of 35.7 g.

The melting point of this compound was 210 to 212° C.

FIG. 8 is an infrared spectrum of the Compound No. 12.

Preparation Example 9

[Synthesis of Compound No. 15 shown in TABLE 1]

19.3 g of 3-nitrophthalic anhydride and 6.2 g of p-xylylene glycol weredispersed in 150 ml of toluene. This reaction mixture was refluxed for 6hours.

After the reaction mixture was cooled to room temperature, the toluenewas distilled away from the reaction mixture under reduced pressure,thereby obtaining a white solid.

The white solid material thus obtained was dispersed in 500 ml of waterand heated to 80° C. Then, the mixture was stirred for 2 hours, andcooled to room temperature.

Thereafter, the mixture was filtered, so that white crystals wereobtained. The white crystals were recrystallized from a 70% aqueoussolution of ethanol, thereby obtaining the Compound No. 15 as whitecrystals in a yield of 3.1 g.

The melting point of this compound was 177 to 180° C.

FIG. 9 is an infrared spectrum of the Compound No. 15.

Preparation Example 10

[Synthesis of Compound No. 22 shown in TABLE 1]

30 g of 3-nitrophthalic anhydride was dispersed in 200 ml of acetic acidto prepare a dispersion of 3-nitrophthalic anhydride. To thisdispersion, 9 g of 1,6-diaminohexane was added in three portions. Theresultant reaction mixture was stirred at room temperature for 3 hours.

After the reaction mixture was poured into 1,000 ml of water and stirredat room temperature, white crystals separated out. The white crystalswere then collected by filtration and washed with water.

The white crystals thus obtained were dispersed in 1,000 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion to adjust the dispersion to pH10 to 11, sothat the white crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjusted the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that the Compound No. 22was obtained as white crystals in a yield of 30.6 g.

The melting point of this compound was 179 to 181° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.09.

FIG. 10 is an infrared spectrum of the Compound No. 22.

Preparation Example 11

[Synthesis of Compound No. 26 shown in TABLE 1]

25 g of 3-nitrophthalic anhydride was dispersed in 200 ml of acetic acidto prepare a dispersion of 3-nitrophthalic anhydride. To thisdispersion, 12.6 g of 4,4′-diaminodiphenylmethane was added in threeportions. The resultant reaction mixture was stirred at room temperaturefor 3 hours.

After the reaction mixture was poured into 1,000 ml of water and stirredat room temperature, light yellow crystals separated out. The lightyellow crystals were then collected by filtration and washed with water.

The light yellow crystals thus obtained were dispersed in 1,000 ml ofwater again. A 10% aqueous solution of sodium hydroxide was addeddropwise to the thus obtained dispersion to adjust the dispersion topH10 to 11, so that the light yellow crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 26 was obtained as light yellow crystals in a yield of 29.7g.

The melting point of this compound was 170 to 173° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.12.

FIG. 11 is an infrared spectrum of the Compound No. 26.

Preparation Example 12

[Synthesis of Compound No. 27 shown in TABLE 1]

25 g of 3-nitrophthalic anhydride was dispersed in 200 ml of acetic acidto prepare a dispersion of 3-nitrophthalic anhydride. To thisdispersion, 13.0 g of 4,4′-diaminodiphenylether was added in threeportions. The resultant reaction mixture was stirred at room temperaturefor 3 hours.

After the reaction mixture was poured into 1,000 ml of water and stirredat room temperature, light yellow crystals separated out. The lightyellow crystals were then collected by filtration and washed with water.

The light yellow crystals thus obtained were dispersed in 1,000 ml ofwater again. A 10% aqueous solution of sodium hydroxide was addeddropwise to the thus obtained dispersion to adjust the dispersion topH10 to 11, so that the light yellow crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 27 was obtained as light yellow crystals in a yield of 31.0g.

The melting point of this compound was 168 to 175° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.12.

FIG. 12 is an infrared spectrum of the Compound No. 27.

Preparation Example 13

[Synthesis of Compound No. 28 shown in TABLE 1]

20 g of 3-nitrophthalic anhydride was dispersed in 200 ml of acetic acidto prepare a dispersion of 3-nitrophthalic anhydride. To thisdispersion, 12.0 g of 4,4′-diaminodiphenylsulfone was added in threeportions. The resultant reaction mixture was stirred at room temperaturefor 3 hours.

After the reaction mixture was poured into 1,000 ml of water and stirredat room temperature, white crystals separated out. The white crystalswere then collected by filtration and washed with water.

The white crystals thus obtained were dispersed in 1,000 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion to adjust the dispersion to pH10 to 11, sothat the white crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that the Compound No. 28was obtained as white crystals in a yield of 26.0 g.

The melting point of this compound was 200 to 202° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.07.

FIG. 13 is an infrared spectrum of the Compound No. 28.

Preparation Example 14

[Synthesis of Compound No. 23 shown in TABLE 1]

25 g of 3-nitrophthalic anhydride was dispersed in 200 ml of acetic acidto prepare a dispersion of 3-nitrophthalic anhydride. To thisdispersion, 15.0 g of 3,3′-diaminodiphenylsulfone was added in threeportions. The resultant reaction mixture was stirred at room temperaturefor 3 hours.

After the reaction mixture was poured into 1,000 ml of water and stirredat room temperature, white crystals separated out. The white crystalswere then collected by filtration and washed with water.

The white crystals thus obtained were dispersed in 1,000 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion to adjust the dispersion to pH10 to 11, sothat the white crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that the Compound No. 23was obtained as white crystals in a yield of 29.5 g.

The melting point of this compound was 188 to 190° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.10.

FIG. 14 is an infrared spectrum of the Compound No. 23.

Preparation Example 15

[Synthesis of Compound No. 28 shown in TABLE 1]

2.0 g of 3-nitrophthalic anhydride was dissolved in 30 ml oftetrahydrofuran to prepare a solution of 3-nitrophthalic anhydride. Tothis solution, 1.2 g of 4,4′-diaminodiphenylsulfone was added in threeportions. The resultant reaction mixture was stirred at room temperaturefor 3 hours, whereby white crystals separated out. The white crystalswere then collected by filtration and washed with water.

The white crystals thus obtained were dispersed in 100 ml of water. A10% aqueous solution of sodium hydroxide was added dropwise to the thusobtained dispersion to adjust the dispersion to pH10 to 11, so that thewhite crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that the Compound No. 28was obtained as white crystals in a yield of 2.4 g.

The melting point, the infrared spectrum, and the R_(f) value of thiscompound were the same as those previously explained in PreparationExample 13.

Preparation Example 16

[Synthesis of Compound No. 23 shown in TABLE 1]

2.0 g of 3-nitrophthalic anhydride was dispersed in 30 ml ofnitrobenzene to prepare a dispersion of 3-nitrophthalic anhydride. Tothis dispersion, 1.2 g of 4,4′-diaminodiphenylsulfone was added in threeportions. The resultant reaction mixture was stirred at room temperaturefor 3 hours, whereby white crystals separated out. The white crystalswere then collected by filtration and washed with hexane.

The white crystals thus obtained were dispersed in 100 ml of water. A10% aqueous solution of sodium hydroxide was added dropwise to the thusobtained dispersion to adjust the dispersion to pH10 to 11, so that thewhite crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that the Compound No. 23was obtained as white crystals in a yield of 2.2 g.

The melting point, the infrared spectrum, and the R_(f) value of thiscompound were the same as those previously explained in PreparationExample 14.

Preparation Example 17

[Synthesis of Compound No. 50 shown in TABLE 1]

50 g of 3-nitrophthalic anhydride was dissolved in 200 ml of aceticanhydride. Part of 3nitrophthalic anhydride remained insoluble anddispersed in the liquid. To this liquid, 14 g of 1,6-diaminohexane wasadded in about 20 portions over a period of about one hour. Theresultant reaction mixture was stirred for 3 hours.

When the reaction mixture was poured into 1,000 ml of water, whitecrystals separated out. The white crystals were then collected byfiltration and washed with water.

The white crystals thus obtained were dispersed in 500 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion to adjust the dispersion to pH10 to 11, sothat the white crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that the Compound No. 50was obtained as white crystals in a yield of 8.0 g.

The melting point of this compound was 173 to 176° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.22.

FIG. 15 is an infrared spectrum of the Compound No. 50.

Preparation Example 18

[Synthesis of Compound No. 54 shown in TABLE 1]

50 g of 3-nitrophthalic anhydride was dissolved in 100 ml of aceticanhydride. Part of 3-nitrophthalic anhydride remained insoluble anddispersed in the liquid. To this liquid, 24 g of4,4′-diaminodiphenylmethane was added in about 20 portions over a periodof about one hour. The resultant reaction mixture was stirred for 3hours.

When the reaction mixture was poured into 1,000 ml of water, lightyellow crystals separated out. The light yellow crystals were thencollected by filtration and washed with water.

The light yellow crystals thus obtained were dispersed in 500 ml ofwater again. A 10% aqueous solution of sodium hydroxide was addeddropwise to the thus obtained dispersion to adjust the dispersion topH10 to 11, so that the light yellow crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 54 was obtained as light yellow crystals in a yield of 12g.

The melting point of this compound was 161 to 165° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.33.

FIG. 16 is an infrared spectrum of the Compound No. 54.

Preparation Example 19

[Synthesis of Compound No. 55 shown in TABLE 1]

50 g of 3-nitrophthalic anhydride was dissolved in 100 ml of aceticanhydride. Part of 3-nitrophthalic anhydride remained insoluble anddispersed in the liquid. To this liquid, 24 g of4,4′-diaminodiphenylether was added in about 20 portions over a periodof about one hour. The resultant reaction mixture was stirred for 3hours.

When the reaction mixture was poured into 1,000 ml of water, lightyellow crystals separated out. The light yellow crystals were thencollected by filtration and washed with water.

The light yellow crystals thus obtained were dispersed in 500 ml ofwater again. A 10% aqueous solution of sodium hydroxide was addeddropwise to the thus obtained dispersion to adjust the dispersion topH10 to 11, so that the light yellow crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 55 was obtained as light yellow crystals in a yield of 25g.

The melting point of this compound was 165 to 168° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.28.

FIG. 17 is an infrared spectrum of the Compound No. 55.

Preparation Example 20

[Synthesis of Compound No. 56 shown in TABLE 1]

50 g of 3-nitrophthalic anhydride was dissolved in 100 ml of aceticanhydride. Part of 3-nitrophthalic anhydride remained insoluble anddispersed in the liquid. To this liquid, 30 g of4,4′-diaminodiphenylsulfone was added in about 20 portions over a periodof about one hour. The resultant reaction mixture was stirred for 3hours.

When the reaction mixture was poured into 1,000 ml of water, whitecrystals separated out. The white crystals were then collected byfiltration and washed with water.

The white crystals thus obtained were dispersed in 500 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion to adjust the dispersion to pH10 to 11, sothat the white crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that a mixture of theCompound No. 56 and the Compound No. 28 was obtained as white crystalsin a yield of 40 g.

Thereafter, the mixture of the Compounds Nos. 56 and 28 was extractedwith 500 ml each of a 30% aqueous solution of ethyl alcohol (with aratio by weight of water to ethyl alcohol of 70:30) for ten times. Theresultant extracted layer was concentrated, thereby obtaining whitecrystals.

These white crystals were dispersed in 200 ml of water. A 10% aqueoussolution of sodium hydroxide was added dropwise to the thus obtaineddispersion to adjust the dispersion to pH10 to 11, so that the whitecrystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that the Compound No. 56was obtained as white crystals in a yield of 12 g.

The melting point of this compound was 172 to 176° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.33.

FIG. 18 is an infrared spectrum of the Compound No. 56.

Preparation Example 21

[Synthesis of Compound No. 51 shown in TABLE 1]

50 g of 3-nitrophthalic anhydride was dissolved in 100 ml of aceticanhydride. Part of 3-nitrophthalic anhydride remained insoluble anddispersed in the liquid. To this liquid, 30 g of3,3′-diaminodiphenylsulfone was added in about 20 portions over a periodof about one hour. The resultant reaction mixture was stirred for 3hours.

When the reaction mixture was poured into 1,000 ml of water, whitecrystals separated out. The white crystals were then collected byfiltration and washed with water.

The white crystals thus obtained were dispersed in 500 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion to adjust the dispersion to pH10 to 11, sothat the white crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that a mixture of theCompound No. 51 and the Compound No. 23 was obtained as white crystalsin a yield of 30 g.

Thereafter, the mixture of the Compounds Nos. 51 and 23 was extractedwith 500 ml each of a 30% aqueous solution of ethyl alcohol (with aratio by weight of water to ethyl alcohol of 70:30) for ten times. Theresultant extracted layer was concentrated, thereby obtaining whitecrystals.

These white crystals were dispersed in 200 ml of water. A 10% aqueoussolution of sodium hydroxide was added dropwise to the thus obtaineddispersion to adjust the dispersion to pH10 to 11, so that the whitecrystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that the Compound No. 51was obtained as white crystals in a yield of 12 g.

The melting point of this compound was 164 to 168° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.37.

FIG. 19 is an infrared spectrum of the Compound No. 51.

Preparation Example 22

(Separation of Compound No. 56 from Compound No. 28)

0.2 g of the mixture of the Compound No. 56 and the Compound No. 28obtained in the course of Preparation Example 20 was subjected toextracting operation at room temperature for 3 hours using 10 ml of asolvent selected from the following solvents:

(1) 20% aqueous solution of ethyl alcohol

(2) 30% aqueous solution of ethyl alcohol

(3) 40% aqueous solution of ethyl alcohol

(4) 50% aqueous solution of ethyl alcohol

In any case, the content of the Compound No. 56 in the extracted layerwas examined by thin-layer chromatography (TLC). As a result, it wasconfirmed that the Compound No. 56 was efficiently extracted when theabove-mentioned solvents (1), (2) and (3) were employed.

Preparation Example 23

(Separation of Compound No. 51 from Compound No. 23)

0.2 g of the mixture of the Compound No. 51 and the Compound No. 23obtained in the course of Preparation Example 21 was subjected toextracting operation at room temperature for 3 hours using 10 ml of asolvent selected from the following solvents:

(1) 20% aqueous solution of ethyl alcohol

(2) 30% aqueous solution of ethyl alcohol

(3) 40% aqueous solution of ethyl alcohol

(4) 50% aqueous solution of ethyl alcohol

In any case, the content of the Compound No. 51 in the extracted layerwas examined by thin-layer chromatography (TLC). As a result, it wasconfirmed that the Compound No. 51 was efficiently extracted when theabove-mentioned solvents (1), (2) and (3) were employed.

Preparation Example 24

[Synthesis of Compound No. 56 shown in TABLE 1]

2.5 g of 3-nitrophthalic anhydride was dissolved in 10 ml of acetone. Tothe above prepared solution of 3-nitrophthalic anhydride, a solutionprepared by dissolving 1.5 g of 4,4′-diaminodiphenylsulfone in 10 ml ofacetone was added dropwise over a period of about 30 minutes.

After the resultant reaction mixture was stirred at room temperature for3 hours, the solvent component was removed from the reaction mixture,thereby obtaining a yellow-brown solid.

The yellow-brown solid material was dispersed in 100 ml of water, and a10% aqueous solution of sodium hydroxide was added dropwise to the thusobtained dispersion to adjust the dispersion to pH10 to 11, so that theyellow-brown solid was dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that 1.5 gof light yellow crystals was obtained.

The melting point of the thus obtained crystals was 160 to 165° C.According to the analysis by thin-layer chromatography (TLC), two spotswere observed. From the R_(f) values and the sizes of the spots, it wasconfirmed that the Compound No. 56 and the Compound No. 28 werecontained in substantially the same amounts.

Preparation Example 25

[Synthesis of Compound No. 56 shown in TABLE 1]

10 g of 3-nitrophthalic anhydride was dissolved in 30 ml of methyl ethylketone. To the above prepared solution of 3-nitrophthalic anhydride, asolution prepared by dissolving 6.4 g of 4,4′-diaminodiphenylsulfone in30 ml of methyl ethyl ketone was added dropwise over a period of about30 minutes.

After the resultant reaction mixture was stirred at room temperature for3 hours, the solvent component was removed from the reaction mixture,thereby obtaining a yellow-brown solid.

The yellow-brown solid material was dispersed in 100 ml of water, and a10% aqueous solution of sodium hydroxide was added dropwise to the thusobtained dispersion to adjust the dispersion to pH10 to 11, so that theyellow-brown solid was dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that 1.3 gof light yellow crystals was obtained.

The melting point of the thus obtained crystals was 168 to 179° C.According to the analysis by thin-layer chromatography (TLC), two spotswere observed. From the R_(f) values and the sizes of the spots, it wasconfirmed that the Compound No. 56 and the Compound No. 28 werecontained in substantially the same amounts.

Preparation Example 26

[Synthesis of Compound No. 54 shown in TABLE 1]

A mixture of 20 g of 3-nitrophthalic acid and 20 ml of acetic anhydridewas dispersed and stirred under the application of heat thereto. Themixture was heated until 3-nitrophthalic acid was dissolved in aceticanhydride. Then, the reaction mixture was allowed to stand at roomtemperature, whereby 3-nitrophthalic anhydride separated out.

To the above reaction mixture, 9.0 g of 4,4′-diaminodiphenylmethane wasadded, and the mixture was stirred at room temperature for 5 hours.After the completion of stirring, the reaction mixture was poured into1,000 ml of water with stirring at room temperature for 8 hours, so thatlight yellow crystals separated out.

The thus obtained crystals were collected by filtration and washed withwater, and then, dispersed in 200 ml of water again. A 10% aqueoussolution of sodium hydroxide was added dropwise to the above prepareddispersion to adjust the dispersion to pH10 to 11, so that the lightyellow crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that 2.0 gof light yellow crystals was obtained.

The melting point of the thus obtained crystals was 154 to 160° C.According to the analysis by thin-layer chromatography (TLC), two spotswere observed. From the R_(f) values and the sizes of the spots, it wasconfirmed that the Compound No. 54 and the Compound No. 16 werecontained in substantially the same amounts.

Preparation Example 27

[Synthesis of Compound No. 56 shown in TABLE 1]

A mixture of 20 g of 3-nitrophthalic acid and 20 ml of acetic anhydridewas dispersed and stirred under the application of heat thereto. Themixture was heated until 3-nitrophthalic acid was dissolved in aceticanhydride. Then, the reaction mixture was allowed to stand at roomtemperature, whereby 3-nitrophthalic anhydride separated out.

To the above reaction mixture, 11.7 g of 4,4′-diaminodiphenylsulfone wasadded, and the mixture was stirred at room temperature for 5 hours.After the completion of stirring, the reaction mixture was poured into1,000 ml of water with stirring at room temperature for 8 hours, so thatwhite crystals separated out.

The thus obtained crystals were collected by filtration and washed withwater, and then, dispersed in 200 ml of water again. A 10% aqueoussolution of sodium hydroxide was added dropwise to the thus obtaineddispersion to adjust the dispersion to pH10 to 11, so that the whitecrystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH2 to 3, whereby whitecrystals separated out. The white crystals thus obtained were washedwith water and dried under reduced pressure, so that 15 g of whitecrystals was obtained.

The melting point of the thus obtained crystals was 162 to 165° C.According to the analysis by thin-layer chromatography (TLC), two spotswere observed. From the R_(f) values and the sizes of the spots, it wasconfirmed that the Compound No. 56 and the Compound No. 28 werecontained in substantially the same amounts.

Preparation Example 28

[Synthesis of Compound No. 26 shown in TABLE 1]

4.9 g of 4,4′-diaminodiphenylmethane was dissolved in 200 ml of tolueneto prepare a solution, and 7.5 g of pyridine was further added to thesolution. To the above prepared mixture, a solution prepared bydissolving 13.4 g of 3-nitro-2-methoxycarbonylbenzoyl chloride in 80 mlof toluene was added dropwise at room temperature.

After completion of the addition, the reaction mixture was stirred for 4hours. Thereafter, the toluene was distilled away from the reactionmixture under reduced pressure, thereby obtaining a yellow liquid.

The yellow liquid thus obtained was poured into 800 ml of ice-cold waterwith stirring, so that 9.0 g of light yellow crystals was obtained.

9.0 g of the light yellow crystals was dispersed in a solution preparedby dissolving 2 g of potassium hydroxide in 100 ml of water, and thedispersion was refluxed for 10 hours. After cooled to room temperature,the dispersion was adjusted to pH2 with dilute hydrochloric acid,whereby the Compound No. 26 was obtained as pale pink crystals in ayield of 3.0 g.

The melting point of this compound was 170 to 175° C.

Preparation Example 29

[Synthesis of Compound No. 27 shown in TABLE 1]

10.0 g of 4,4′-diaminodiphenylmethane was dissolved in 100 ml ofdimethylformamide to prepare a solution, and 13.0 g of pyridine wasfurther added to the solution. To the above prepared mixture, a solutionprepared by dissolving 26.2 g of 3-nitro-2-methoxycarbonylbenzoylchloride in 100 ml of dimethylformamide was added dropwise at roomtemperature.

After completion of the addition, the reaction mixture was stirred for 4hours. Thereafter, the dimethylformamide was distilled away from thereaction mixture under reduced pressure, and the reaction mixture waspoured into 800 ml of water, thereby obtaining 14.3 g of an orangesolid.

14.0 g of the orange solid material thus obtained was dispersed in asolution prepared by dissolving 5 g of potassium hydroxide in 200 ml ofwater, and the dispersion was refluxed for 10 hours. After cooled toroom temperature, the dispersion was adjusted to pH2 with dilutehydrochloric acid, whereby the Compound No. 27 was obtained as lightyellow crystals in a yield of 5.0 g.

The melting point of this compound was 175 to 178° C.

Preparation Example 30

[Synthesis of Compound No. 28 shown in TABLE 1]

10.0 g of 4,4′-diaminodiphenylmethane was dissolved in 200 ml of methylethyl ketone to prepare a solution, and 8.6 g of pyridine was furtheradded to the solution. To the above prepared mixture, a solutionprepared by dissolving 22.0 g of 3-nitro-2-methoxycarbonylbenzoylchloride in 100 ml of methyl ethyl ketone was added dropwise at roomtemperature.

After completion of the addition, the reaction mixture was stirred for 4hours. Thereafter, the methyl ethyl ketone was distilled away from thereaction mixture under reduced pressure, and the reaction mixture waspoured into 800 ml of water, thereby obtaining 25.0 g of an orangeviscous material.

25.0 g of the orange viscous material thus obtained was dispersed in asolution prepared by dissolving 4.5 g of potassium hydroxide in 300 mlof water, and the dispersion was refluxed for 10 hours. After cooled toroom temperature, the dispersion was adjusted to pH2 with dilutehydrochloric acid, whereby the Compound No. 28 was obtained as lightyellow crystals in a yield of 11.6 g.

The melting point of this compound was 191 to 194° C.

Preparation Example 31

[Synthesis of Compound No. 50 shown in TABLE 1]

2.9 g of 1,6-hexamethylenediamine was dissolved in 50 ml of toluene toprepare a solution, and 7.5 g of pyridine was further added to thesolution. To the above prepared mixture, a solution prepared bydissolving 13.4 g of 2-nitro-6-methoxycarbonylbenzoyl chloride in 50 mlof toluene was added dropwise at room temperature.

After completion of the addition, the reaction mixture was stirred for 4hours. Thereafter, the toluene was distilled away from the reactionmixture under reduced pressure, and the reaction mixture was poured into800 ml of water, thereby obtaining 9.1 g of yellow-white crystals.

9.1 g of the yellow-white crystals thus obtained were dispersed in asolution prepared by dissolving 3.8 g of potassium hydroxide in 150 mlof water, and the dispersion was refluxed for 10 hours. After cooled toroom temperature, the dispersion was adjusted to pH2 with dilutehydrochloric acid, whereby the Compound No. 50 was obtained as whitecrystals in a yield of 1.6 g.

The melting point of this compound was 145 to 148° C.

Preparation Example 32

[Synthesis of Compound No. 54 shown in TABLE 1]

2.7 g of 4,4′-diaminodiphenylmethane was dissolved in 200 ml of tolueneto prepare a solution, and 10.0 g of pyridine was further added to thesolution. To the above prepared mixture, a solution prepared bydissolving 10.0 g of 2-nitro-6-methoxycarbonylbenzoyl chloride in 80 mlof toluene was added dropwise at room temperature.

After completion of the addition, the reaction mixture was stirred for 4hours. Thereafter, the toluene was distilled away from the reactionmixture under reduced pressure, so that a yellow liquid was obtained.

The yellow liquid thus obtained was poured into 800 ml of ice-cold waterwith stirring, thereby obtaining 8.0 g of pale yellow crystals.

8.0 g of the pale yellow crystals was dispersed in a solution preparedby dissolving 10 g of potassium hydroxide in 300 ml of water, and thedispersion was refluxed for 10 hours. After cooled to room temperature,the dispersion was adjusted to pH2 with dilute hydrochloric acid,whereby the Compound No. 54 was obtained as light yellow crystals in ayield of 3.0 g.

The melting point of this compound was 170 to 174° C.

Preparation Example 33

[Synthesis of Compound No. 55 shown in TABLE 1]

10.0 g of 4,4′-diaminodiphenylether was dissolved in 200 ml ofdimethylformamide to prepare a solution, and 13.0 g of pyridine wasfurther added to the solution. To the above prepared mixture, a solutionprepared by dissolving 26.2 g of 2-nitro-6-methoxycarbonylbenzoylchloride in 100 ml of dimethylformamide was added dropwise at roomtemperature.

After completion of the addition, the reaction mixture was stirred for 4hours. Thereafter, the dimethylformamide was distilled away from thereaction mixture under reduced pressure, and the reaction mixture waspoured into 800 ml of water, thereby obtaining 19.3 g of a yellow solid.

19.3 g of the yellow solid material thus obtained was dispersed in asolution prepared by dissolving 5 g of potassium hydroxide in 200 ml ofwater, and the dispersion was refluxed for 10 hours. After cooled toroom temperature, the dispersion was adjusted to pH2 with dilutehydrochloric acid, whereby the Compound No. 55 was obtained as pale pinkcrystals in a yield of 5.0 g.

The melting point of this compound was 162 to 165° C.

Preparation Example 34

[Synthesis of Compound No. 56 shown in TABLE 1]

10.0 g of 4,4′-diaminodiphenylsulfone was dissolved in 200 ml of methylethyl ketone to prepare a solution, and 13.0 g of pyridine was furtheradded to the solution. To the above prepared mixture, a solutionprepared by dissolving 20.0 g of 2-nitro-6-methoxycarbonylbenzoylchloride in 100 ml of methyl ethyl ketone was added dropwise at roomtemperature.

After completion of the addition, the reaction mixture was stirred for 4hours. Thereafter, the methyl ethyl ketone was distilled away from thereaction mixture under reduced pressure, and the reaction mixture waspoured into 800 ml of water, thereby obtaining 15.0 g of an orangeviscous material.

15.0 g of the orange viscous material thus obtained was dispersed in asolution prepared by dissolving 3.0 g of potassium hydroxide in 300 mlof water, and the dispersion was refluxed for 10 hours. After cooled toroom temperature, the dispersion was adjusted to pH2 with dilutehydrochloric acid, whereby the Compound No. 56 was obtained as pale pinkcrystals in a yield of 11.6 g.

The melting point of this compound was 175 to 179° C.

Preparation Example 35

[Synthesis of Compound No. 123 shown in TABLE 1]

40 g of trimellitic anhydride was dispersed in 250 ml of acetic acid toprepare a dispersion of trimellitic anhydride. To this dispersion, 25.0g of 4,4′-diaminodiphenylsulfone was added for three times. Theresultant reaction mixture was stirred at room temperature for 3 hours.

After the reaction mixture was poured into 1,000 ml of water and stirredat room temperature, white crystals separated out. The white crystalswere then collected by filtration and washed with water.

The white crystals thus obtained were dispersed in 1,000 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion so as to dissolve the white crystalstherein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate, whereby white crystals separated out. The whitecrystals thus obtained were washed with water and dried under reducedpressure, so that 53.0 g of an intermediate No. 1 represented by thefollowing formula was obtained.

The melting point of this intermediate No. 1 was 231 to 235° C.According to the analysis by thin-layer chromatography (TLC), the R_(f)value of this compound was 0.06.

7.0 g of the above obtained intermediate was dissolved in 30 ml ofdimethyl sulfoxide to prepare a solution. To this solution, 2.4 g ofsodium carbonate was added with stirring, whereby a dispersion wasobtained. To this dispersion, a solution prepared by dissolving 3.5 g ofethyl bromide in 10 ml of dimethyl sulfoxide was added dropwise at roomtemperature. The thus obtained reaction mixture was heated on a waterbath of 80° C. with stirring for 12 hours, with 1.0 g of ethyl bromidebeing further added in two portions to the reaction mixture.

The resultant reaction mixture was poured into 400 ml of water, and a10% aqueous solution of hydrochloric acid was added dropwise to themixture, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 123 was obtained as white crystals in a yield of 4.5 g.

The melting point of this compound was 143 to 148° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.10.

Preparation Example 36

[Synthesis of Compound No. 131 shown in TABLE 1]

The intermediate No. 1 was synthesized in the same manner as describedin Preparation Example 35.

7.0 g of the above obtained intermediate No. 1 was dissolved in 30 ml ofdimethyl sulfoxide to prepare a solution. To this solution, 2.4 g ofsodium carbonate was added with stirring, whereby a dispersion wasobtained. To this dispersion, a solution prepared by dissolving 3.8 g ofbenzyl bromide in 10 ml of dimethyl sulfoxide was added dropwise at roomtemperature. The thus obtained reaction mixture was heated on a waterbath of 90 to 95° C. with stirring for 12 hours.

The resultant reaction mixture was poured into 400 ml of water, and a10% aqueous solution of hydrochloric acid was added dropwise to themixture, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 131 was obtained as white crystals in a yield of 4.1 g.

The melting point of this compound was 144 to 147° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.15.

Preparation Example 37

[Synthesis of Compound No. 395 shown in TABLE 1]

23.0 g of 4-hydroxyphthalic anhydride was dissolved in 100 ml of aceticacid to prepare a solution. To this solution, 13.5 g of4,4′-diaminodiphenylmethane was added in small portions. The thusobtained reaction mixture was stirred for 2 hours.

The resultant reaction mixture was poured into 1,000 ml of water, sothat light yellow crystals separated out. The crystals were collected byfiltration and washed with water.

The light yellow crystals were dispersed in 500 ml of water again and a10% aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 395 was obtained as white crystals in a yield of 29.0 g.

The melting point of this compound was 167 to 171° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.28.

Preparation Example 38

[Synthesis of Compound No. 407 shown in TABLE 1]

7.0 g of 4-hydroxyphthalic anhydride was dissolved in 50 ml of aceticacid to prepare a solution. To this solution, 5.0 g of4,4′-diaminodiphenylsulfone was added in a small portions. The thusobtained reaction mixture was stirred for 2 hours.

The resultant reaction mixture was poured into 500 ml of water, so thatwhite crystals separated out. The crystals were collected by filtrationand washed with water.

The white crystals were dispersed in 500 ml of water again and a 10%aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 407 was obtained as white crystals in a yield of 9.5 g.

The melting point of this compound was 183 to 187° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.11.

Preparation Example 39

[Synthesis of Compound No. 413 shown in TABLE 1]

7.0 g of 4-hydroxyphthalic anhydride was dissolved in 50 ml of aceticacid to prepare a solution. To this solution, 5.0 g of3,3′-diaminodiphenylsulfone was added in small portions. The thusobtained reaction mixture was stirred for 2 hours.

The resultant reaction mixture was poured into 500 ml of water, so thatwhite crystals separated out. The crystals were collected by filtrationand washed with water.

The white crystals were dispersed in 500 ml of water again and a 10%aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 413 was obtained as white crystals in a yield of 8.6 g.

The melting point of this compound was 185 to 190° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.11.

Preparation Example 40

[Synthesis of Compound No. 400 shown in TABLE 1]

7.0 g of the Compound No. 43 was dissolved in 30 ml of pyridine toprepare a solution. To this solution, 9.0 g of p-toluenesulfonic acidchloride was added in small portions, with special care being exercisedto prevent the sudden increase of the temperature of the reactionsystem. The thus obtained reaction mixture was heated for one hour so asto maintain the temperature of the reaction system at 45° C., andthereafter poured into 200 ml of ice-cold water, so that milky whitecrystals separated out. The crystals were collected by filtration andwashed with water.

The milky white crystals were dispersed in 200 ml of water again and a10% aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby pale pink crystals separated out. The pale pinkcrystals were washed with water and dried under reduced pressure, sothat the Compound No. 400 was obtained as pale pink crystals in a yieldof 4.7 g.

The melting point of this compound was 144 to 150° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.06.

Preparation Example 41

[Synthesis of Compound No. 396 shown in TABLE 1]

17.0 g of 4-(2-phenoxyethyleneoxy)phthalic anhydride was dissolved in100 ml of acetic acid to prepare a solution. To this solution, 5.5 g of4,4′-diaminodiphenylmethane was added in small portions. The thusobtained reaction mixture was stirred for 5 hours, and thereafter pouredinto 1,000 ml of water, so that pale brown crystals separated out. Thecrystals were collected by filtration and washed with water.

The pale brown crystals were dispersed in 500 ml of water again and a10% aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 396 was obtained as white crystals in a yield of 18.1 g.

The melting point of this compound was 128 to 131° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.20.

Preparation Example 42

[Synthesis of Compound No. 668 shown in TABLE 1]

16.0 g of phthalic anhydride was dissolved in 100 ml of acetic acid toprepare a solution. To this solution, 15.0 g of2,2-bis(4-aminophenoxy)propylidene was added in small portions. The thusobtained reaction mixture was stirred for 2 hours, and thereafter pouredinto 700 ml of water, so that gray-white crystals separated out. Thecrystals were collected by filtration and washed with water.

The gray-white crystals were dispersed in 500 ml of water again and a10% aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 668 was obtained as white crystals in a yield of 22.7 g.

The melting point of this compound was 155 to 158° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.20.

Preparation Example 43

[Synthesis of Compound No. 663 shown in TABLE 1]

10.5 g of phthalic anhydride was dissolved in 100 ml of acetic acid toprepare a solution. To this solution, 15.0 g ofbis(4-aminophenoxyphenyl)sulfone was added in small portions. The thusobtained reaction mixture was stirred for 2 hours, and thereafter pouredinto 700 ml of water, so that gray-white crystals separated out. Thecrystals were collected by filtration and washed with water.

The gray-white crystals were dispersed in 500 ml of water again and a10% aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 663 was obtained as white crystals in a yield of 22.1 g.

The melting point of this compound was 181 to 185° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.15.

Preparation Example 44

[Synthesis of Compound No. 673 shown in TABLE 1]

11.5 g of phthalic anhydride was dissolved in 100 ml of acetic acid toprepare a solution. To this solution, 15.0 g of2,2-bis(4-aminophenoxyphenyl)propylidene was added in small portions.The thus obtained reaction mixture was stirred for 2 hours, andthereafter poured into 700 ml of water, so that white crystals separatedout. The crystals were collected by filtration and washed with water.

The white crystals were dispersed in 500 ml of water again and a 10%aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby white crystals separated out. The white crystals werewashed with water and dried under reduced pressure, so that the CompoundNo. 673 was obtained as white crystals in a yield of 21.7 g.

The melting point of this compound was 141 to 148° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.20.

Preparation Example 45

[Synthesis of Compound No. 671 shown in TABLE 1]

20.0 g of phthalic anhydride was dissolved in 100 ml of acetic acid toprepare a solution. To this solution, 16.0 g ofbis(4-amino-2-ethylphenyl)methane was added in small portions. The thusobtained reaction mixture was stirred for 2 hours, and thereafter pouredinto 700 ml of water, so that light yellow crystals separated out. Thecrystals were collected by filtration and washed with water.

The light yellow crystals were dispersed in 500 ml of water again and a10% aqueous solution of sodium hydroxide was added dropwise to thedispersion so as to dissolve the crystals therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to thefiltrate, whereby light yellow crystals separated out. The light yellowcrystals were washed with water and dried under reduced pressure, sothat the Compound No. 671 was obtained as light yellow crystals in ayield of 27.9 g.

The melting point of this compound was 144 to 147° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.15.

Preparation Example 46

[Synthesis of Compound No. 532 shown in TABLE 1]

7.0 g of phthalic anhydride and 9.1 g of 4-nitrophthalic anhydride weredissolved in 100 ml of acetic acid. Part of anhydrides remainedinsoluble and dispersed in the liquid. To this liquid, 11.0 g of4,4′-diaminodiphenylsulfone was added in small portions. The resultantreaction mixture was stirred for 2 hours.

When the reaction mixture was poured into 1,000 ml of water, lightyellow crystals separated out. The crystals were then collected byfiltration and washed with water.

The light yellow crystals thus obtained were dispersed in 500 ml ofwater again. A 10% aqueous solution of sodium hydroxide was addeddropwise to the thus obtained dispersion to adjust the dispersion topH10 to 11, so that the light yellow crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH3 to 4, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 532 was obtained as light yellow crystals in a yield of21.2 g.

The melting point of this compound was 168 to 172° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.30.

Preparation Example 47

[Synthesis of Compound No. 523 shown in TABLE 1]

10.0 g of 4-hydroxyphthalic anhydride and 12.0 g of 4-nitrophthalicanhydride were dissolved in 100 ml of acetic acid. Part of anhydridesremained insoluble and dispersed in the liquid. To this liquid, 11.9 gof 4,4′-diaminodiphenylmethane was added in small portions. Theresultant reaction mixture was stirred for 2 hours.

When the reaction mixture was poured into 500 ml of water, light yellowcrystals separated out. The crystals were then collected by filtrationand washed with water.

The light yellow crystals thus obtained were dispersed in 500 ml ofwater again. A 10% aqueous solution of sodium hydroxide was addeddropwise to the thus obtained dispersion to adjust the dispersion topH10 to 11, so that the light yellow crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH3 to 4, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 523 was obtained as light yellow crystals in a yield of20.7 g.

The melting point of this compound was 160 to 164° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.20.

Preparation Example 48

[Synthesis of Compound No. 522 shown in TABLE 1]

7.0 g of phthalic acid and 9.1 g of 4-nitrophthalic anhydride weredissolved in 100 ml of acetic acid. Part of anhydrides remainedinsoluble and dispersed in the liquid. To this liquid, 9.0 g of4,4′-diaminodiphenylmethane was added in small portions. The resultantreaction mixture was stirred for 4 hours.

When the reaction mixture was poured into 500 ml of water, light yellowcrystals separated out. The crystals were then collected by filtrationand washed with water.

The light yellow crystals thus obtained were dispersed in 500 ml ofwater again. A 10% aqueous solution of sodium hydroxide was addeddropwise to the thus obtained dispersion to adjust the dispersion topH10 to 11, so that the light yellow crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH3 to 4, whereby lightyellow crystals separated out. The light yellow crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 522 was obtained as light yellow crystals in a yield of18.8 g.

The melting point of this compound was 154 to 156° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.20.

Preparation Example 49

[Synthesis of Compound No. 521 shown in TABLE 1]

9.0 g of phthalic anhydride and 10.0 g of 4-hydroxyphthalic anhydridewere dissolved in 150 ml of acetic acid. Part of anhydrides remainedinsoluble and dispersed in the liquid. To this liquid, 11.0 g of4,4′-diaminodiphenylmethane was added in small portions. The resultantreaction mixture was stirred for 2 hours.

When the reaction mixture was poured into 500 ml of water, light browncrystals separated out. The crystals were then collected by filtrationand washed with water.

The light brown crystals thus obtained were dispersed in 350 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion to adjust the dispersion to pH10 to 11, sothat the light brown crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH3 to 4, whereby lightbrown crystals separated out. The light brown crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 521 was obtained as light brown crystals in a yield of 19.7g.

The melting point of this compound was 150 to 155° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.05.

Preparation Example 50

[Synthesis of Compound No. 528 shown in TABLE 1]

9.0 g of phthalic acid and 10.0 g of 4-hydroxyphthalic anhydride weredissolved in 150 ml of acetic acid. Part of anhydrides remainedinsoluble and dispersed in the liquid. To this liquid, 13.0 g of4,4′-diaminodiphenylsulfone was added in small portions. The resultantreaction mixture was stirred for 2 hours.

When the reaction mixture was poured into 600 ml of water, light browncrystals separated out. The crystals were then collected by filtrationand washed with water.

The light brown crystals thus obtained were dispersed in 500 ml of wateragain. A 10% aqueous solution of sodium hydroxide was added dropwise tothe thus obtained dispersion to adjust the dispersion to pH10 to 11, sothat the light brown crystals were dissolved therein.

The thus obtained solution was subjected to filtration, and a 10%aqueous solution of hydrochloric acid was added dropwise to theresultant filtrate to adjust the filtrate to pH3 to 4, whereby lightbrown crystals separated out. The light brown crystals thus obtainedwere washed with water and dried under reduced pressure, so that theCompound No. 528 was obtained as light brown crystals in a yield of 25.0g.

The melting point of this compound was 168 to 173° C. According to theanalysis by thin-layer chromatography (TLC), the R_(f) value of thiscompound was 0.05.

In the previously mentioned Preparation Examples, the melting point ofthe compound was measured using a commercially available micro meltingpoint apparatus, made by Yanaco Co., Ltd. In addition, the TLC analysiswas carried out using a commercially available chromato plate “KODAKChromatogram Sheet 13181 Silica Gel (with fluorescent indicator)”(Trademark), and a mixed solvent of ethyl acetate and ethyl alcohol witha ratio by volume of 1:1 as a developing solution. After the developingsolvent was dried, the chromato plate was exposed to ultraviolet lightto detect the spot of the compound. The flow rate expressed by the R_(f)value was obtained in accordance with the following formula:${R_{f}\quad {value}} = \frac{{Developing}\quad {distance}\quad {of}\quad a\quad {spot}\quad {of}\quad {compound}}{{Developing}\quad {distance}\quad {of}\quad {developing}\quad {solution}}$

The aromatic carboxylic acid compounds according to the presentinvention are novel and useful as the color developers for use in thethermosensitive recording material. When such an aromatic carboxylicacid compound is used as the color developer in the thermosensitiverecording material, the preservation stability of recorded images,particularly in terms of plasticizer resistnace is remarkably improved.

In addition, the aforementioned aromatic carboxylic acid compound can beproduced efficiently by the method of the present invention.

Japanese Patent Application No. 09-233381 filed Aug. 14, 1997, JapanesePatent Applications Nos. 09-323851 and 09-323852 filed Nov. 10, 1997,Japanese Patent Applications Nos. 09-335141 and 09-335142 filed Nov. 19,1997, Japanese Patent Application No. 09-344162 filed Nov. 27, 1997,Japanese Patent Application No. 09-356211 filed Dec. 9, 1997, JapanesePatent Applications Nos. 09-364686 and 09-364687 filed Dec. 18, 1997,Japanese Patent Application No. 10-042936 filed Feb. 9, 1998, JapanesePatent Application No. 10-098156 filed Mar. 27, 1998 and Japanese PatentApplication No. 10-153632 filed May 18, 1998 are hereby incorporated byreference.

What is claimed is:
 1. A thermosensitive recording material comprising asupport and a thermosensitive coloring layer formed thereon comprising aleuco dye and a color developer capable of inducing color formation insaid leuco dye upon application of heat thereto, with said colordeveloper comprising at least one compound (A) having in a moleculethereof at least two aromatic ring moieties selected from the groupconsisting of: (i) an aromatic ring moiety having at least one carboxylgroup and at least one electron-attracting functional group, (ii) anaromatic ring moiety having at least one carboxyl group and at least oneelectron-donating functional group, and (iii) an aromatic ring moietyhaving at least one carboxyl group, free of said electron-attractingfunctional group and said electron-donating functional group, at leasttwo of said aromatic ring moieties in said compound (A) being bonded byeither ester linkage or amide linkage, provided that from compoundshaving two of said aromatic ring moieties (iii) serving as said compound(A), a compound of formula (B) is excluded:

 wherein G is —C_(n)H_(2n−2)— (in which n is an integer of 2 to 6),

 (in which n is an integer of 2 to 6),


2. The thermosensitive recording material as claimed in claim 1, whereinat least two of said aromatic ring moieties for use in said compound (A)are bonded by ester linkage.
 3. The thermosensitive recording materialas claimed in claim 2, wherein said aromatic ring moieties in themolecule of said compound (A) are different.
 4. The thermosensitiverecording material as claimed in claim 2, wherein saidelectron-attracting functional group is selected from the groupconsisting of nitro group and ester group.
 5. The thermosensitiverecording material as claimed in claim 2, wherein said electron-donatingfunctional group is selected from the group consisting of hydroxylgroup, alkoxyl group and sulfonyloxy group.
 6. The thermosensitiverecording material as claimed in claim 1, wherein at least two of saidaromatic ring moieties for use in said compound (A) are bonded by amidelinkage.
 7. The thermosensitive recording material as claimed in claim6, wherein said aromatic ring moieties in the molecule of said compound(A) are different.
 8. The thermosensitive recording material as claimedin claim 6, wherein said electron-attracting functional group isselected from the group consisting of nitro group and ester group. 9.The thermosensitive recording material as claimed in claim 6, whereinsaid electron-donating functional group is selected from the groupconsisting of hydroxyl group, alkoxyl group and sulfonyloxy group. 10.The thermosensitive recording material as claimed in claim 1, whereinsaid compound (A) has in the molecule thereof at least two aromatic ringmoieties (i).
 11. The thermosensitive recording material as claimed inclaim 10, wherein at least two of said aromatic ring moieties (i) arebonded by ester linkage.
 12. The thermosensitive recording material asclaimed in claim 10, wherein at least two of said aromatic ring moieties(i) are bonded by amide linkage.
 13. The thermosensitive recordingmaterial as claimed in claim 10, wherein said electron-attractingfunctional group is selected from the group consisting of nitro groupand ester group.
 14. The thermosensitive recording material as claimedin claim 1, wherein said compound (A) has in the molecule thereof atleast two aromatic ring moieties (ii).
 15. The thermosensitive recordingmaterial as claimed in claim 14, wherein at least two of said aromaticring moieties (ii) are bonded by ester linkage.
 16. The thermosensitiverecording material as claimed in claim 14, wherein at least two of saidaromatic ring moieties (ii) are bonded by amide linkage.
 17. Thethermosensitive recording material as claimed in claim 14, wherein saidelectron-donating functional group is selected from the group consistingof hydroxyl group, alkoxyl group and sulfonyloxy group.
 18. Thethermosensitive recording material as claimed in claim 1, wherein saidaromatic ring moieties in the molecule of said compound (A) aredifferent.
 19. The thermosensitive recording material as claimed inclaim 1, wherein said electron-attracting functional group is selectedfrom the group consisting of nitro group and ester group.
 20. Thethermosensitive recording material as claimed in claim 1, wherein saidelectron-donating functional group is selected from the group consistingof hydroxyl group, alkoxyl group and sulfonyloxy group.
 21. Thethermosensitive recording material as claimed in claim 1, wherein saidcompound having two of said aromatic ring moieties (iii) serving as saidcompound (A) is of formula (C):

wherein X is;

or —(C_(n)H_(2n))— in which n is an integer of 1 to 3; and R is methylgroup, ethyl group or a halogen atom.
 22. The thermosensitive recordingmaterial. as claimed in claim 1, further comprising an intermediatelayer which is provided between said support and said thermosensitivecoloring layer.
 23. The thermosensitive recording material as claimed inclaim 22, wherein said intermediate layer comprises minute sphericalvoid particles which comprise a thermoplastic resin.